[BUG #7779] making qx.Website artifacts version-string free

- can be re-enabled using the VERSION_STRING macro in .json files
- (.html files need to be adapted by hand)
[BUG #7779] adapting 'website' skeleton

- retain version strings in file names for script/ artefacts
- let api/, test/ scripts be version-free
- also: using local test/script/q.min.js for test/index.html
  (instead of outside ../script/q.js)
[BUG #7779] retain version tags in 'server' skeleton files
[BUG #7779] make component/server file names version-free

- also re-worked the config 'export' list
[BUG #7779] fixed clean, distclean for website and its skeleton
[BUG #7779] switched website tutorial to non-versioned lib
[BUG #7779] adapt Makefile.release

- apply version strings when creating download lib
  (for <vers>/framework/q-<vers>.min.js, etc.)
- create download zip archive with versioned file names
- (also eliminating unnecessary 'script/' subfolder in archive)
- expect non-versioned file names from repo
[BUG #7779] adapted 'todo' app to non-versioned libs
[BUG #7779] removed version-independent files from bumpqxversion.py
[BUG #7779] extracted the code for versionification into a make macro

- this is pure text replacement and works with shell vars
- as a by-product another macro that works only with make variables
  (currently not used)