This introduces the unset() command to make it easy to unset CMake
variables, environment variables, and CMake cache variables.  Previously
it was not even possible to unset ENV or CACHE variables (as in
completely remove them).  Changes based on patch from Philip Lowman.
See issue #7507.

ENH:                                                                                                                                                                     ~/CMake/src/Docs
* Additions for cmake-command highligting.
* Additions for operator-highlighting

Alex

seems to fix the issues mentioned in the bug report and the rest also still
seems to be ok

Alex

ENH: Using suggestion from Stuart Herring to avoid needing a list of command names in the highlighting table.

ENH: More system variables, more operators, more commands, fix some string issues and some cmake arguments issues

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.