make ptp scripts enter alt on start if alt not already active, restore previous state on exit. Fixes camera not responding to canon or alt mode keys after running ptp scripts.
ptp alt handling - make enter_alt/exit_alt override saved state, cleanup and comments
update ptp protocol header documentation
S110 & G15 updates from c10ud:
http://chdk.setepontos.com/index.php?topic=650.msg102636#msg102636
Convert SX50 to use code_gen & add remote capture support (filewrite.c).
Update for finsig_dryos.c to find timer functions from srsa_4c.
http://chdk.setepontos.com/index.php?topic=6560.msg102564#msg102564
SX220 remote capture support from msl:
http://chdk.setepontos.com/index.php?topic=650.msg102652#msg102652