Drop #end and #module. Convert #section to a subsection header.
Convert #variable to the cmake domain "variable" directive.
Convert #macro to the cmake domain "command" directive.
Perform minor formatting fixes in text near these changes.
If CPACK_NSIS_ENABLE_UNINSTALL_BEFORE_INSTALL is set to ON the NSIS installer will look for a previous installed version and ask the user about uninstall.
Allows custom NSIS commands to run prior to any installation
actions. Projects that need to run an uninstaller first,
especially one from a non-NSIS previous revision of a project
that is NOW using CPack and NSIS, may do so by putting custom
NSIS commands into this variable.
Inspired-by: David Golub