Add support for the Pentax K110D

(cherry picked from commit ca627577c7897cff28ec68b0dd426429e3d0d19a)
masks : allow to move first segment of brushes

(cherry picked from commit fb0ac62c558e00654092c92ecd326a54e614a1ea)
Better names for key accels (no more <Primary>)

(cherry picked from commit 0bee981f4a3cf9a4619f74930f64eff5d996efb5)
dt_init(): check argc: do not over-read

Fixes a crash when DT is started:
$ darktable --conf
Reported by Pedro Côrte-Real

(cherry picked from commit 2690212cd911128bd12d6dda5a68853241b3544f)
Add support for the Pentax *ist DS to rawspeed

(cherry picked from commit 6785f2b74d1178560c6e794c50f1cb35cb097866)