* Repository avatars

- first variant of code from old work for gogs
- add migration 87
- add new option in app.ini
- add en-US locale string
- add new class in repository.less

* Add changed index.css, remove unused template name

* Update en-us doc about configuration options

* Add comments to new functions, add new option to docker app.ini

* Add comment for lint

* Remove variable, not needed

* Fix formatting

* Update swagger api template

* Check if avatar exists

* Fix avatar link/path checks

* Typo

* TEXT column can't have a default value

* Fixes:

- remove old avatar file on upload
- use ID in name of avatar file - users may upload same files
- add simple tests

* Fix fmt check

* Generate PNG instead of "static" GIF

* More informative comment

* Fix error message

* Update avatar upload checks:

- add file size check
- add new option
- update config docs
- add new string to en-us locale

* Fixes:

- use FileHEader field for check file size
- add new test - upload big image

* Fix formatting

* Update comments

* Update log message

* Removed wrong style - not needed

* Use Sync2 to migrate

* Update repos list view

- bigger avatar
- fix html blocks alignment

* A little adjust avatar size

* Use small icons for explore/repo list

* Use new cool avatar preparation func by @lafriks

* Missing changes for new function

* Remove unused import, move imports

* Missed new option definition in app.ini

Add file size check in user/profile avatar upload

* Use smaller field length for Avatar

* Use session to update repo DB data, update DeleteAvatar - use session too

* Fix err variable definition

* As suggested @lafriks - return as soon as possible, code readability

* UI: Make document body a flexbox

Fixes: https://github.com/go-gitea/gitea/issues/6118

* ie11 fixes

* increase padding to 80px

* add flex-grow

* Viewport meta tag

* responsive: dashboard

* responsive: issues page

* responsive: Explore page

* responsive: navbar, and some navbar css refactoring

* responsive: button for collapsing navbar in mobile view

* Mark the hamburger button as active when pressed

* better homepage for responsive views

* Bring back jump class in navbar

The class was necessary, because this way the
dropdown doesn't assume the contents of the
selected item.

* make repository homes responsive

* Make file view page responsive

* Make forms look good on responsive views

* make commits and commit diff view responsive

* issues and PRs

* responsive wiki

* Don't place auto-init far off the page

* Minor changes to amend broken stuff

minor improvements

- make login/sign up in navbar stackable
- make navbar in explore and sign in not stackable

Change selected class in TestPullCompare

Fix typo that happened when rebasing

fix dashboard on org view

improve profile UI

Use clearing on file diff to fix broken UI caused by floating elements

remove unresolved merge conflict, and | Sanitize

Fix repo home not loading

* Add branch overiew page

* fix changed method name on sub menu

* remove unused code

* Take navbar out of column
* Add styles to navbar
* Changed navbar classes
* Remove unneeded !important from index.css
* Remove unneeded !important from _explore.less

Both are possible on explore and admin panel

This does not change any content and generated gogs.css is still the same.