New features
------------

CMake's `AUTOMOC` and `AUTOUIC` now cache information extracted when parsing
source files in `CMakeFiles/<ORIGIN>_autogen.dir/ParseCache.txt`.
This leads to faster `<ORIGIN>_autogen` target rebuilds, because source files
will be parsed again only if they're newer than the `ParseCache.txt` file.
The parse cache will be recomputed if it is older than the CMake executable.

`AUTOMOC` and `AUTOUIC` now check if `moc` or `uic` output files are older
than the `moc` or `uic` executable.  If an output file is older than the
compiler, it will be regenerated.  Therefore if a new `moc` or `uic` version
is installed, all output files will be regenerated.

`AUTOMOC` and `AUTOUIC` error and warning messages are more detailed.

Internal changes
----------------

`moc` and `uic` output file names are not computed in the `_autogen`
target anymore but in `cmQtAutoGenInitializer`.  This makes the available at
the configur...