SciDAVis - Improvements SVN-temp

- 3rdparty cleanup: Removed unused misleading zlib stuff and
updated liborigin from its SVN repos
- improved README.html (license section) and renamed it to
INSTALL.html which IHMO fits better
- added a plain text README containing the the most
important information about SciDAVis
- added a CHANGES file to contain future changelogs
- adjusted scidavis.pro accordingly

- wrote the "Translating SciDAVis" section

- some more corrections/improvements to the German translation

- added German phrase book to use with Qt linguist
- improved and completed the German translation
- removed QObject::tr() from format strings

- fixed some typos
- worked on the German translation

- made a new icon for "add/remove curves"
- removed many unnecessary occurences of the prefix "SciDAVis - "

- Removed script window.
- Reorganized tool bars.
- Plot tool buttons also work on Graphs (they change the last curve on the active layer).

add index

add index for main terms

- ran lupdate for all translations
- worked a little bit on the German translation