Cmake build: Add combo-values to the list of displayed lyx options
Combine OutlineIn and OutlineOut blocks

They differ only by adding/subtracting 1.
Cmake build: Early check for wrong combo values
Cmake build: Use LYX_COMBO() to select the qt-version to use.

Collaboration with Scott Kostyshak
Fix typo
Improve file saving strategy

- The TempFile class guarantees to generate a file name, we are not limited to
  100 tries of a predictable scheme anymore, which could break if LyX
  frequently crashes.
- The temp file name generation has no race condition against another LyX
  instance in the same directory anymore.
- Symlinks survive saving again (regression of 10364082c835).
Don't double delete by making TempFile noncopyable

The compiler generated copy constructor and assignment operator are wrong.
This could easily be fixed by implementing them manually, but a) they are
not needed, and b) the semantics would be unclear (should the copy point
to a new temp file or not?), so it is better to forbid them.
Remove unsafe method FileName::tempName()

FileName::tempName() created a new temp file name by using qt to create a
temporary file with a unique name, and then deleting that file and returning
the name. This was unsafe, since other processes or even other threads of the
running LyX could create files with the same name between deletion and then
using the temp name.
This is fixed by using the TempFile class instead. As a side effect, a few
cases where the temp files were not deleted after usage were fixed as well.
The only place that is still unsafe is createTmpDir().
Fix wrong "externally modified" message

This was a regression of 10364082c835.
Fix thinko in loop detection