* Add CreateGitVersionHeader.cmake to extract git version information to create the kicad version
header.
* Add check for .git folder in source path to trigger git version CMake macro.
* Use CMake add_custom_target() to run WriteVersionHeader.cmake as a command.
* Modify WriteVersionHeader.cmake to be run as a command instead of a macro.
* Add version header creation as a CMake common library build dependency.
* Add cached CMake variable KICAD_BUILD_VERSION when build version is defined during
configuration.
* Fix CMake macro create_bzr_version_header to always update version.h file whenever a repo change
is found. Running `make rebuild_cache is no longer required.
* Add new CMake function for writing version.h file.
* Always use version.h file for build version string instead of meaningless hard coded date.
* Only use bzr version string when build version is not defined at configuration time for stable release
version strings.
* Minor cleanup of FindBazaar.cmake.
* Remove unnecessary version.h.cmake file.
Nick Østergaard
Wayne Stambaugh