Improved transitions (#642)

* Improved transitions

Code quality improvements.
Shape transitions now all scale down to 0 instead of 16 (mario and bowser).
Ease in was added which leads to far smoother transitions.
HD_TRANSITIONS define added, makes use of the tex edge render mode to deliver smooth transition textures.
lerpf was added to math utils.

* Cleaner textures, rounding only during vertex creation

* Another attempt

* cozies naming suggestion

* Improvements and suggestions

SHARP_TRANSITION_TEXTURES is now off by default (I still think the textures for it could be improved).
lerpf, to_smoothstop, smoothstart, smoothstop and smoothstep have all been added.
make_vertex has been inlined.
make_simple_vertex has been added (colourless vertex).
Transition colors (and canon colors) are now defined using primative colour instead of setting individual vertices color´s.
Transition´s now use smoothstep (ease-in-out) instead of ease out only.
Naming has been improved.

* Proper function inling and removal of GBI_FLOATS variant of make_vertex and make_simple_vertex

* More requested changes

* Accidental final new line removal fixed

* Comment about pop in fix.

* Comment fix

The issue with writing comments for stuff is when you want to change code later on.

include/config/config_graphics.h

@@ -138,7 +138,7 @@
 /**
  * Limits the horizontal fov on emulator like on console. May break viewport widescreen hacks.
  */
-//#define HORIZONTAL_CULLING_ON_EMULATOR
+// #define HORIZONTAL_CULLING_ON_EMULATOR
 
 /**
  * Makes objects bellow the screen be culled.
@@ -150,3 +150,13 @@
  * will be used instead.
  */
 #define DEFAULT_CULLING_RADIUS 300
+
+/**
+ * Eases the textured screen transitions to make them look smoother.
+ */
+#define EASE_IN_OUT_TRANSITIONS
+
+/**
+ * Makes use of the tex edge render mode to deliver smooth transition textures
+ */
+// #define SHARP_TRANSITION_TEXTURES