BUG: Avoid adding unused rules to special targets like ALL_BUILD.  Make sure project regeneration rules go only in desired targets.

BUG: Fixed generation of VS8 solution file to not be re-written when loaded by VS and to work with msbuild.

ENH: Added INSTALL command as a placeholder for a future generic install specification interface.  Currently it supports only a SCRIPT option specifying a script to run during the install stage.

BUG: Fixed bootstrap from MSYS prompt.  It was working only when the bootstrap directory in MSYS mapped to the same directory on windows except for the drive letter in front.  Now it should work from any path.

ENH: Made Check* modules more consistent and well documented.  Added CMAKE_REQUIRED_DEFINITIONS option.