The included hunspell should not be used on Linux or OS X, but (depending on
local configuration) it might be needed for crosscompiling a mingw target
from Linux. Now the user can choose whether to use the included hunspell or not.
cmake does already support that.
Now the only other dependency you need to cross-compile for mingw on debian
or ubuntu is qt.
The new 3rdparty libraries are not added to the autotools build system, so
that they appear in the source package. They cannot be compiled yet with
autotools (although this would make sense for cross compilation with mingw),
but adding configure support for enabling/disabling these like we do for
boost is a bit more work, so I did not do it for now. Nevertheless, the
three new Makefile.am are already prepared for compilation.
