MSVC takes a lot of time if all warnings are enabled, mostly just to
print them.
Disable "all warnings" for Windows only. The deafault warnings are still
listed.
* Modify travis config
Get the required version of cmake binaries from their website.
* Travis config modification
Add librt linking because of old glibc in precise.
* Travis modify config
Changing LibRt binding for cmake.
* [trial] Travis config simplify
Remove unused variables
