Log Message:
librecad: Update to 2.2.0.rc2. Fixed build with latest boost.

"More than 280 commits since 2.2.0-rc1 and too much delay, but here it is,
the next big step to final 2.2.0 release.  We fixed some really serious
bugs with DWG reading, what hopefully leads to much less issues and crashes
when opening DWG files.  There may be still some issues with DWG we want to
address and fix for the final 2.2.0 release."