Slider upgrades
This patch adds a generic slider that can be used for GRAPH_OT_decimate and for the pose sliders in pose_slide.c.
It also implements it to pose_slide.c
Usage
- an operator that wants to use this slider needs to save a pointer to tSlider. An initialized *tSlider is returned from ED_slider_create for that
- modal operations should use ED_slider_init after create to set the needed values for mouse movement calculation
- call ED_slider_modal to update the percentage value and the drawing
- use ED_slider_status_string_get to get a string with help info that can be printed to the status bar
- use ED_slider_destroy to free the memory and remove the drawing callback
- use ED_slider_factor_get and ED_slider_factor_set for accessing the calculated factor
- use ED_slider_allow_overshoot_get and ED_slider_allow_overshoot_set to disallow overshoot. some operators don't handle values beyond the 0-1 range