a530: fix the free space display related function addresses - from srsa_4c in http://chdk.setepontos.com/index.php?topic=650.msg103248#msg103248
remove unused variables, from nafraf in http://chdk.setepontos.com/index.php?topic=650.msg103238#msg103238
remove unneeded spytask functions, from nafraf in http://chdk.setepontos.com/index.php?topic=650.msg103250#msg103250
Restore special case for low ISO handling for G12 & SX30 (in case it's needed in future).
remove directory inadvertently added in r2986
remote capture - don't use uncached address for dng header, possible fix for corrupt headers
fix warning in previous commit