The GCC version used by Travis is old and appears not to support all the
warnings we would like to get, so reenable Clang. Additionally make lots
of cleanups to Travis config and make the build a lot faster too.
Also change both Travis and AppVeyor builds to treat warnings as errors,
and include VS2017 in the matrix for AppVeyor. I have also removed
VS2010 because it is ancient at this point.
Updated Premake to alpha12 and fixed the premake build file
appropriately.
* Tests live in a "Tests" folder alongside the other components. Inside the "Tests" folder, tests are split into folders by the component they test. For example, the example unit test of "rcVdot" (which is implmemented in Recast/Recast.h) lives in "Tests/Recast/Tests_Recast.h".
* Uses the Catch testing framework
* One example test of "rcVdot"
* Tests are run on Travis and Appveyor after every build. Failing unit tests will fail the build in both case.
* Added instructions on running unit tests to the readme
* Renamed a bunch of variables in main.cpp to be more descriptive.
* Removed unnecessary SDLMain.h and SDLMain.m OSX objective-c class as well as the plist, strings, xib and icns files, which are not needed.
* included cstdio in imguiRenderGL since SDL2 doesn't do it for us.
* Updated premake5 script to support SDL2 and to set the debug directory, as well as copy the SDL2.dll to the target directory on Windows.
* Updated readme with more descriptive, platform-specific demo project setup instructions
* Updated appveyor build script to build vs2015 as well.
* Updated Travis build script to build SDL2 from source, because they use Ubuntu 12.04 which doesn't have the libsdl2-dev package in its repositories.
Build scripts download SDL, download (or build) premake5, generate projects, then build, in several configurations and platforms
Project now builds with premake5 instead of premake4 to allow VS2015 project generation
Tweaked SDL directory dependency to work better with CI
Update README
