* Fix warning C4244 in src/layer/normalize.cpp

C4244: '=': conversion from 'double' to 'float', possible loss of data

* Fix warning C4244 in src/layer/requantize.cpp

C4244: 'initializing': conversion from 'double' to 'int', possible loss of data

* Fix warning C4244 in src/mat_pixel_resize.cpp

C4244: '=': conversion from 'double' to 'int', possible loss of data

* Fix warning C4244 in src/mat_pixel.cpp

C4244: '=': conversion from 'int' to 'float', possible loss of data

* Fix warning C4267 in src/modelbin.cpp

C4267: 'initializing': conversion from 'size_t' to 'int', possible loss of data

* Fix warning C4244 in src/layer/batchnorm.cpp

C4244: 'initializing': conversion from 'double' to 'float',
    possible loss of data

* Fix warning C4244 in src/layer/padding.cpp

C4244: 'argument': conversion from 'const float' to 'T', possible loss of data

* Fix warning C4244 in src/layer/priorbox.cpp

C4244: '=': conversion from 'double' to 'float',
    possible loss of data
C4244: 'initializing': conversion from 'double' to 'float',
    possible loss of data