-> Replace the three bool params with an enum
-> Add struct for the static content, leads to less repetition
-> cache enable_animations setting

Fix non coding style conforming glb_fontengine to g_fontengine
Fix fonts never been deleted due to grabbed to often

Add DPI support for statbar
Move heart+bubble bar to Lua HUD
Add statbar size (based upon an idea by blue42u)
Add support for customizing breath and statbar

Add support for (configurable) multiline hotbar
Improved screensize handling
Add userdefined gui scale by BlockMen

On the lua side, notably minetest.env:<function>(<args>) should now
be replaced by minetest.<function>(<args>).
The old way is and will stay supported for a long time.

Also:
Update and clean up lua_api.txt (by celeron55)
Move EnvRef to lua and remove add_rat and add_firefly (by kahrl)
Add separate src/util/CMakeLists.txt, other minor fixes (by kahrl)

Fix health bar overlap when a larger texture is used