compiler warnings

[FuccDucc]

Hi,

There are quite a few warnings in this projects that might be worth investigating and checking for incorrect usage/potential bugs arising from them. All line numbers below correspond to unmodified master @ 7113f4e

zopfli\src\zopfli\hash.c(53): warning C4267: '=': conversion from 'size_t' to 'unsigned short', possible loss of data
zopfli\src\zopfli\hash.c(69): warning C4267: '=': conversion from 'size_t' to 'unsigned short', possible loss of data
zopfli\src\zopfli\hash.c(125): warning C4267: '=': conversion from 'size_t' to 'unsigned short', possible loss of data
zopfli\src\zopfli\squeeze.c(243): warning C4305: '=': truncation from 'double' to 'float'
zopfli\src\zopfli\squeeze.c(264): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopfli\squeeze.c(281): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopfli\squeeze.c(299): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopfli\squeeze.c(300): warning C4267: '=': conversion from 'size_t' to 'unsigned short', possible loss of data
zopfli\src\zopfli\cache.c(70): warning C4267: '=': conversion from 'size_t' to 'unsigned char', possible loss of data
zopfli\src\zopfli\lz77.c(360): warning C4267: '=': conversion from 'size_t' to 'unsigned short', possible loss of data
zopfli\src\zopfli\lz77.c(486): warning C4267: '=': conversion from 'size_t' to 'unsigned short', possible loss of data
zopfli\src\zopfli\deflate.c(638): warning C4267: '=': conversion from 'size_t' to 'unsigned short', possible loss of data
zopfli\src\zopfli\zopfli_bin.c(119): warning C4013: '_setmode' undefined; assuming extern returning int
zopfli\src\zopflipng\lodepng\lodepng.cpp(128): warning C4551: function call missing argument list
zopfli\src\zopflipng\lodepng\lodepng.cpp(741): warning C4267: '=': conversion from 'size_t' to 'unsigned short', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng.cpp(765): warning C4267: '=': conversion from 'size_t' to 'unsigned short', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng.cpp(782): warning C4267: '=': conversion from 'size_t' to 'unsigned short', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(546): warning C4244: 'return': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(724): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(725): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(726): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(750): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(751): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(752): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(753): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(754): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(755): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(756): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(757): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(758): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(809): warning C4305: 'initializing': truncation from 'double' to 'const float'
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(814): warning C4305: 'initializing': truncation from 'double' to 'const float'
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(819): warning C4305: 'initializing': truncation from 'double' to 'const float'
zopfli\src\zopflipng\lodepng\lodepng_util.cpp(824): warning C4305: 'initializing': truncation from 'double' to 'const float'

CC @lvandeve as some warnings concern lodepng