Remove support for non-TTF fonts

This patch set removes support in TWRP for the old .dat file
format as well as support for the AOSP style fonts in header
files. We need TTF for scaling.

Note that the old AOSP style header font is still supported in
minui which is not used by TWRP.

Change-Id: I6124a3333d479f1fc668138f7e32c4be9b519552