[travis] clang test
[os_net] null terminate buffer in 'OS_RecvConnUDP'
[travis] add fast_finish; exclude windows build and clang compiler
[travis] add comment for change
[travis] fix linux agent build
Merge pull request #266 from cgzones/travis

travis improvements.
[config] update makefile
[config] fix compiler warnings
[config] remove duplicate if else branch
[config] fix allocater mismatches
[config] remove dead code
[config] fix build: define global variable
[config] fix conversion warning
[config] fix missing prototype
[config] add some explicit casts
[config] add some const qualifiers
[config] fix possible memory leaks
[config] remove unused function 'AssignIgnore_Global'
[config] qualify some void pointers
[config] add some nonnull qualifiers