More extensions to script interface:

- obj_fadeAlphaWithLife()
- obj_setOverrideRenderPass()
- setLayerRenderPass()
- debugBreak()
- saveMenu()
- setGemPosition()
- removeGem()
Correct wrong mod precache logic
Add support for suppressing game actions from being handled, minor changes to actions

This allows to e.g. prevent ACTION_TOGGLEHELPSCREEN from being handled by
the game, and instead use a node's catch action functionality to handle the event.

Add related Lua functions:
- setIgnoreAction()
- isIgnoreAction()
- sendAction()
Implement node messaging (node_msg() function); there is no reason entities have this but nodes do not.

Also made node script error messages a bit nicer.