added freetype text rendering (still buggy)

this allows to render glyphs and also brings a simple
engine for rendering UTF-8 strings onto the framebuffer.
blitting to uneven offset is implemented here, too, but
needs more work and is still buggy.

In the end, this will allow for a simple GUI.

rendertext_example.lua

@@ -0,0 +1,17 @@
+require "rendertext"
+
+fb = einkfb.open("/dev/fb0")
+width, height = fb:getSize()
+
+print("open")
+
+face = freetype.newBuiltinFace("Helvetica", 64)
+print("got face")
+
+renderUtf8Text(100,100,face,"h","Hello World! äöü")
+
+fb:refresh()
+
+while true do
+	local ev = input.waitForEvent()
+end