Revert "Always use double, not float, for real type"

This reverts commit 5d22c91356d0f490bf8c3e954ae51f8e8de44d8a.

Conflicts:

	fontforgeexe/startnoui.c
	m4/fontforge_arg_enable.m4
Revert some sweeping code changes that might break merges.
Missed one.
Disable broken blob.
Remove a few more merge-breaking things.