Blender Git Loki

uiLists enhacements: dragresize and better GRID layout.

Many thanks to Brecht for the review!

* You can now drag-resize uiLists (in default or grid layouts).
** Note about "default" size: when you drag below minimal size of the uiList, it will automatically reset to automatic sizing (i.e. size between rows and maxrows, depending on the number of items to show). This often means (e.g. in Materials list with many mat slots) that the list will grow again to maxrows!

* Grid uiLists now have a customizable number of columns (previously it was a fixed value of 9), and they will respect the rows/maxrows settings as well (i.e. show a scrollbar when needed), instead of growing indefinitly!