Enhance included bios tables.

Moved floppy parameter table to its 0xefc7 location.
Define floppy base table as a struct.
Cleaned up definitions in romlayout.S
Fixed bug in handle_15c0 - wasn't clearing cf.
Clean up some post.c usages of bios tables.
diff --git a/TODO b/TODO
index bd3bbe9..b633512 100644
--- a/TODO
+++ b/TODO
@@ -1,5 +1,7 @@
 Find out why ubuntu compiles are failing.  Find work around.
+Audit all sti/cli calls.
 Code assumes ebda segment is static - it doesn't read 0x40e.
 See if using an ld script for 16bit mode is a good idea.
@@ -9,8 +11,6 @@
 Fix makefiles so that they rebuild the required files automatically.
-Make sure gdt/idt tables are properly aligned
 Cleanup setting of ES on GET/SET_BDA
 Make sure inline assembly isn't preventing inlining of calling