Added a lot more configurations in the CI, and fixed some stuff.

[FranckRJ]

• Added more versions of GCC and Clang.
• Tests now run for MSVC.
• Test several C++ standard instead of only the default one of the compiler.
• Test are not ran by default, their building need to be enabled manually.
• Disabled appveyor.

MSVC tests run in 32 bits, because the 64 bits mode doesn't work with RTTI related features : #196. MSVC tests currently don't run C++14-specific tests, even if compiled in C++14. I guess it's because of the thing about __cplusplus define not being defined but I'm not sure.

Will fix parts of #269.

[coveralls]

Coverage: 99.925%. Remained the same when pulling bdd884e2b9dc2b6dc9d6d8def8e09f5a39a10d1a on improve-CI-more-tests into 83d5989b259ca5df1c784de6a412e2d0ed44ef3a on dev.