Re-enable translation of pdfpages help text (works around #9045)

Note that this is not a string change in l7n sense (see discussion in #9045)
Fixing #7987: deleted text in change-tracking mode is not found in Advanced F&R any more.

Merged Paragraph::stringify into asString().
Added ignore of deleted text to Advanced F&R.
id.po: port translations from branch

as service for Waluyo to save some work
Update it.po
elsarticle: use standard xampl bib from texmf tree (relative path does not work for templates)
* cs.po shortcut conflict
Fix display of predefined macros (bug #9059)

This was a regression of e86cdc40: A newly introduced member variable was
not initialized in the constructor, which made it quite random whether symbols
like \coloneqq where displayed correctly or as an empty edit box.
installer: commit files with which installer for RC1 was built

- known problem: if LyX 2.0.x is installed and you install 2.1rc1, the .lyx file associations will not be updated but if LyX 2.1 is installed on a new PC the file associations work (work is in progress)
xypic.lyx: updates from Jean-Pierre
Fix problem with python and change of PATH

- waits that lyxrc has been read before finding python
- when the PATH changes, resets the value
Revert "Fixing #7987: deleted text in change-tracking mode is not found in Advanced F&R any more."

This reverts commit cb351665f432671eb263eec76164aa546abd7151.
installer: fix a bug with file associations

- this fixes the bug I mentioned in my previous installer commit
template files: remove relative paths

this re-enables the feature to use them as "new from template"
template files: remove all relative paths to re-eanable to use "new from template"

- this brings back all our template files (they are no example files, would have been a regression otherwise because LyX 2.0 offers them already in "new from template")
- the thesis files will stay in the examples folder for now until we have a real fiix for bug #8643
partly revert commit a860d18b5a722606c68fb1a4ec22ffe3e99792e6

svmono and svmult must stay in the examples folder because they include childs
Release notes: Warn Windows users to not use Qt 4.8.5