[Gtkradiant] Crash fix patches for trunk

[Markus Fischer]

Hi,

I thought I'm going to communicate some patches, I assume it's not like
everyone is jumping onto github not and watching the commits. I'm
sparing the feature additions I'm doing for now, as I don't know what
the goals of trunk at id are anyway.

Compilation error on Windows with VC++2008 Express. Not sure if it's
really necessary or if it's just my setup; Linux wasn't affected.
http://github.com/mfn/GtkRadiant/commit/cb83767629e61c3753e0d760f2a7fa90362a332e.diff


Fix crash when no game configuration or installation packs were found
http://github.com/mfn/GtkRadiant/commit/b729ef16153a984be2847ec310e3ffa5ebe1d938.diff


Fix race condition crash: cannot open prefs when no game is selected.
That change is rather big for what it does, may not be appropriate and
well, isn't that necessary anyway.
http://github.com/mfn/GtkRadiant/commit/e11933c7b11d67e4a11ca63ecca808203df6e684.diff


Fix crash in model plugin when shut down.	
http://github.com/mfn/GtkRadiant/commit/d68efd997c66bbe88bfbba431e8aa69e7f96d84c.diff


[Linux] Fix crash and data loss when saving shader, report by Rambetter.
http://github.com/mfn/GtkRadiant/commit/625a42c77551351f5821468351b9d6ef2bb41a24.diff

[Linux] Fix attempt: models with upper case letters in the path are not
shown, reported by Rambetter.
http://github.com/mfn/GtkRadiant/commit/4ae38a57e61bda27e99d75001400892931c28c62.diff


All things I worked on so far are listed in
http://github.com/mfn/GtkRadiant/blob/mfn/NEWS .

regards,
- Markus