Added option to clear the editor or not

I propose to test the necessity of cleaning the editor
We need unlock editor even if hasn't cleared editor
Welder class fix

Now change of Welder.Category should not change techRequired
RE-FIX for "minor fix in techRequired dropdown "

re-fix for 70760b460545c1246fa49b310b4bae6109a617da
Now contentList.Add call has found it's right place
minor GUI improvments
Merge pull request #36 from girka2k/dev-test

Dev test