Bugs to fix:
-  A few key hits ignored after leaving the application  (could not reproduce)
-  Lost keyboard control at startup                      (could not reproduce)
-  Influence of keyboard on some timers and RTC (maybe interrupt priority)
-  Alignment of ALL .data / .rodata files is required to ensure converted data
   is properly aligned

Simple improvements:
-  demo:	Try 284x124 at (-60, -28) (all disadvantages)
-  display:	Rectangle-based drawing functions
-  time:	Compute CLOCKS_PER_SEC
-  string:	Use cmp/str to implement memchr() (assembler examples)
-  string:	Do some tests for memcmp()
-  core:	Register more interrupts (and understand their parameters)
-  project:	Clean headers that have some internal definitions
-  project:	Check size of all library structures
Larger improvements:
-  errno:	Introduce errno and use it more or less everywhere
-  bopti:	Monochrome bitmaps blending modes
-  bopti:	Handle partial transparency
-  core:	Implement all callbacks and a complete user API
*  core:	Better save registers
*  core:	Allow return to menu
-  serial:	Implement a driver
-  usb:		Implement a driver
-  esper:	Cleaner playback, synthetizing
-  clock:	Handle overclocking (relaunch clocks when overclocking)
-  project:	Unify this hellish mess of register access!

Things to investigate:
-  Packed bit fields alignment
-  Registers that may need to be saved within setjmp()
-  Registers that may need to be saved and restored by gint
-  Optimizing core/gint.c leads to raising of an illegal slot exception when
   running the interrupt handler, although it ends on rte; lds.l @r15+, mach,
   which is totally not an illegal slot.
-  Check version registers on SH7705