Don't clear the textbox, focus it instead. We want the user to see the wrong input instead of a blank textbox.

Fix #926

Use singleton mode for hotkey callbacks.

If user manually deleted servers from gui-config.json

Merge 'Switch to PAC' and 'Switch to Global'

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Also, fix typo in ProxyForm

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- Use readonly object as lock

Info from stackoverflow:

If I want to be sure that it will be locked for all threads inside my
application:
The lock object has to be static, if it locks access to static state.
Otherwise it has to be instance, because there's no need to lock state of
one class instance, and prevent other threads to work with another class
instance at the same time.

everyone says that the object has to be "readonly" I didn't found the
reason
Well, it doesn't have to be. This is just a best practice, which helps you
to avoid errors.

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

* Add HTTP proxy support in forward proxy

Signed-off-by: noisyfox <timemanager.rick@gmail.com>

* Typo

* Throw exception if forward proxy not supported.

>_<

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- Use insert instead and move to newly inserted
  item instead of the last one after operation

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Squashed commit of the following:

commit 48eb4d8839
Author: Syrone Wong <wong.syrone@gmail.com>
Date:   Sun Sep 18 15:46:09 2016 +0800

    Drop useless interface impl

    Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

commit c0a4f3421a
Author: Logan Zhou <xorcererzc@gmail.com>
Date:   Sun Sep 18 00:58:02 2016 +0800

    Revert "Updated to meet the hint from Wongsyrone."

    This reverts commit 84c8053577.

commit 84c8053577
Author: Logan Zhou <xorcererzc@gmail.com>
Date:   Sun Sep 18 00:52:21 2016 +0800

    Updated to meet the hint from Wongsyrone.

commit 333ccb6d1f
Author: Logan Zhou <xorcererzc@gmail.com>
Date:   Sun Sep 18 00:34:52 2016 +0800

    Added duplicate button to config form.

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Design:

Use the plain string for both config and hotkey parsing
and make use of KeyConverter, ModifierKeysConverter
to make it more rubust.

Find corresponding label (to display operation result) and callback (to do the real work) based on textbox name. In this case, they should be named as `<Feature-Name><Control-Name>`.

ShowLogsTextBox,
ShowLogsLabel,
ShowLogsCallback.

If this requirement doesn't meet, throw an exception at runtime.

Logic:

How to input keys:
1. put focus in the corresponding textbox
2. press the key combination you want to use
3. when you think it is ready, release all keys
4. the textbox shows your input

How to change keys:
1. put focus in the corresponding textbox
2. press BackSpace to clear content
3. re-input new one

How to deactivate:
1. clear content in the textbox
2. press OK button

Meaning of label color:
- Green: this combination is not occupied by other programs and register successfully
- Yellow: this combination is occupied by other programs and you have to change to another one
- Transparent without color: initial status

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- Only use one instance of LogForm

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

* optimize LogMessageTextBox

* StringBuilder instead

- Save empty config if null ref
- only save config when clicking OK button

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- Move to seperate model

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

* new traffic chart style
- remove invoke
- force to set AxisY.Maximum not zero
- format LogForm.cs

* avoid data race

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- Revert bandwidthScale when throughput gets smaller
- Don't save coordinates when LogForm is minimized. Otherwise, we get negative values
- activate ConfigForm & ProxyForm & LogForm

User wants to use that server after selected it in the ConfigForm. If user deletes
the server in use, we can't find its index, then the previous logic will revert to
index 0, which is not expected behaviour.

Since we handled 'ServersListBox.SelectedIndex' in various event handlers, we can
trust it all the time.

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: noisyfox <timemanager.rick@gmail.com>

- add event handler for KeyDown
- drop unused code, we don't support
  table and rc4 now

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

- Drop redundant code.
  I should read code carefully, mbed TLS will set operation
  when invoking mbedtls_cipher_setkey(), the last param
  const mbedtls_operation_t operation is what we want.
- minor changes

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

日志相关修改

* Refine encryption

- Add AES-CTR, blowfish and camellia ciphers

aes-256-ctr
aes-192-ctr
aes-128-ctr
bf-cfb
camellia-128-cfb
camellia-192-cfb
camellia-256-cfb

- Merge the previous PolarSSL and MbedTLS
- Switch to MbedTLS's cipher layer functions
- Add workaround to set cipher operation(encrypt/decrypt)

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

* Add function to get MbedTLS cipher context size

and drop hard-coded ctx sizes

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

日志文件越来越大，原有的清空日志只是清理记录窗口中显示的日志，实际并没有真的删除。

User requested.

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>