Icons tweaked #4469

- The "light" icon theme is now a little lighter, to increase contrast.
- Toolbox icons are now small.
- Buttons:
  - Buttons without labels which use icons as their only source of info regarding what the button does (e.g. the white-balance pipette button) use normal-sized icons.
  - Labeled buttons which use icons as an auxiliary source of information (e.g. Auto-Crop) now use small icons. Curve type icons are also small even though they have no labels.
- Colored circles are smaller.
- Curve type icons redesigned and small.
- Hand icons (when panning the preview) redesigned to have a clear outline regardless of background color.
- Magnifier icons redesigned to have a thinner magnifier frame and larger inner parts.
- Perspective, distortion and crop icons redesigned.
- Some small icons were missing the `-small` suffix, now renamed.

rtgui/crop.cc

@@ -128,7 +128,7 @@ Crop::Crop():
     pack_start (*hb2, Gtk::PACK_SHRINK, 4);
 
     selectCrop = Gtk::manage (new Gtk::Button (M("TP_CROP_SELECTCROP")));
-    selectCrop->set_image (*Gtk::manage (new RTImage ("crop.png")));
+    selectCrop->set_image (*Gtk::manage (new RTImage ("crop-small.png")));
 
     pack_start (*selectCrop, Gtk::PACK_SHRINK, 2);