This commit mainly introduces an almost-normal sysroot where the
compiler and libs will be installed. This is done in order to properly
build libstdc++-v3 from the GCC tree while also cleaning up the
slightly chaotic current install system.
* Add an `fxsdk --version` command
* Redo the README like a translation of the French topic
* Up default project to gint 2.9 to help get migrations right
* Add new `fxsdk path` command reporting important folders
* Add new CMake variables FXSDK_SYSROOT, FXSDK_INCLUDE, FXSDK_LIB so
CMake can access the information of `fxsdk path`
* fxSDK is now in charge of removing the entire sysroot including the
cross-compiler
* Add a LICENSE file
