Use WelsSnprintf instead of SNPRINTF
Use WelsVsnprintf instead of VSPRINTF
Fix a typo Millsecond -> Millisecond
Use WelsGetTimeOfDay and WelsStrftime instead of LOCALTIME/FTIME/strftime
Merge pull request #238 from mstorsjo/merge-snprintf-strftime-wrappers

Use WelsSnprintf/WelsVsnprintf/WelsGetTimeOfDay/WelsStrftime instead of inconsistent macros