Implement SDF fonts. (#24)

* Initial SDF font generation work.

* Text now correctly displaying with proper spacing.

* Fix untextured draws, implement custom rectangles.

* Fix regular image display.

* Slightly refactor ImGui rendering.

* Implement outlines.

* Implement bevel.

* Create host device after loading the module if the installer wasn't run.

* Move ImGui files to its own folder.

* Fix outline sizes.

* Fix default ImGui font and font scales.

* Update font atlas files.

.gitmodules

@@ -13,3 +13,6 @@
 [submodule "UnleashedRecompResources"]
 	path = UnleashedRecompResources
 	url = https://github.com/hedge-dev/UnleashedRecompResources.git
+[submodule "thirdparty/msdf-atlas-gen"]
+	path = thirdparty/msdf-atlas-gen
+	url = https://github.com/Chlumsky/msdf-atlas-gen.git