* app/color_cmds.c: moved a bunch of PDB stuff here

* app/color_balance.[ch]: removed PDB proc, exported TransferMode
enum, ColorBalanceDialog, color_balance_create_lookup_tables, and
color_balance

* app/curves.[ch]: removed PDB procs, exported SMOOTH and GFREE
#defines, CurvesDialog, curves_lut_func and curves_calculate_curve

* app/desaturate.[ch]: removed PDB proc, exported desaturate

* app/equalize.[ch]: removed PDB proc, exported equalize

* app/histogram_tool.[ch]: removed PDB proc, exported HISTOGRAM_WIDTH
and HISTOGRAM_HEIGHT #defines, HistogramToolDialog,
histogram_tool_histogram_range

* app/hue_saturation.[ch]: removed PDB proc, exported HueRange enum,
HueSaturationDialog, hue_saturation_calculate_transfers,
hue_saturation

* app/invert.[ch]: remove PDB proc, export invert

* app/threshold.[ch]: remove PDB proc, export ThresholdDialog and
threshold_2

* internal_procs.c: changes for pdbgen

* app/gimprc.c: removed leftover declaration

* app/image_map.h: add #...