Merge pull request #14 from tangbo2013/develop

impl xopengl.h / xgl.h / xfont.h
 add api: xrand/xtapi
Merge pull request #21 from gaolele5911/xtapiAndxrand2

merge xtapi and xrand2.
add time function
Merge pull request #26 from caiywHub/feature_1

add time function
add file: sys_xgldef.h
add fun: xthread_sleep
Merge pull request #27 from guangbin79/add_xgl_def_header

add file: sys_xgldef.h
Merge pull request #28 from guangbin79/add_thread_sleep_fun

add fun: xthread_sleep
mkdir: iOS \ Android
modify xC headers file in src.