Merge pull request #256 from nem0/stuff

Terrain editor
Merge pull request #259 from nem0/stuff

Grass
Merge pull request #260 from nem0/stuff

Some minor stuff
Merge pull request #261 from nem0/stuff

Entity templates and undo/redo
Merge pull request #268 from nem0/stuff

Stuff
Merge branch 'master' of github.com:nem0/LumixEngine into stuff
editable resource's properties in the property grid