Renamed all the "vibe" package to "vibecompat" to avoid conflicts.

Added rudimentary support for the --arch= option and moved build type flag generation to a common place.

Added a new "build" generator that directly invokes the compiler. ...

This generator supports all compilers in contrast to the rdmd based one and will later be the default.

Added LDC support and improved compiler name maching (e.g. gdc-2.061 is now matched with gdc)

Also added support for gdmd and ldmd

Implemented basic multi-compiler support (with only a dmd implementation right now).