freemind: 0.9.0 -> 1.0.1

See http://freemind.sourceforge.net/wiki/index.php/FreeMind_1.0.0:_The_New_Features
for an overview of changes in version 1.

Tested briefly by creating, saving & loading a simple mind map. The
problems referred to in the previous version of the build recipe
do not occur for me.

This patch simplifies the build somewhat, but it could still be improved
by not copying the freemind dist wholesale into nix-support and replacing
freemind.sh with a more specialized wrapper.