Introducing a panel for additional custom keys for easier access to special keyboard characters

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25500 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Automatic update of propset svn:ignore via for svnignore.txt's by svnignore

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25501 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Improved the code for algebra view size.

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@25502 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e