Short term :
------------

General
  - Fix init mode (ah=00). Should use more BIOS variables
  - Add new functionalities and modify static functionality table
  - Performance : 16 bits IO

v1.0
  - Implement the remaining functions (don't know if all are needed):
    - select alternate print screen routine ah=12 bl=20
    - display switch interface ah=12 bl=35
  - Bugfixes


===============================================================================
VBE:
----
Long term:
- VGA compatible mode numbers for VBE modes
- Text io functions in VBE modes > 8 bpp

