Store all colors in LdCanvasPrivate and initialize them upon
object creation. This creates a base for color themes.
Make attempts to try adding an object that's not a part
of the document to the selection issue a warning.
This required creating a simple framework for operations to LdCanvas.
It is probable that it's going to require some changes when other
operations are added. The basic idea behind it seems to be good, though.
* Set the working directory for glib-genmarshal correctly.
* Use one more path suffix when searching for glibconfig.h.
* Don't assume that gdk_screen_get_resolution() returns
a useful value.
* Rename ld_canvas_translate_*_coordinates() to ld_canvas_*_to_*_coords().
* Add missing parameter assertions to those functions.
* Rename local variables in draw_grid().
* Use gdk_cairo_rectangle() in expose-event handler.
* Update comments.
* Add missing asserts to exported functions.
* Unify formatting.
* Fix the gtk-doc comment for ld_symbol_category_set_human_name().
* Make ld_library_load() reflect it's declaration.
* Remove an unused variable in ld_library_load_cb().
* Change all char's to gchar's.
1. Add methods for coordinate translation between cairo/GtkWidget
coordinates and LdDocument coordinates.
2. Draw the grid correctly (also make it significantly faster).
3. Place the canvas into a GtkScrolledWindow and register
the set_scroll_adjustments signal in the GtkWidget base class.
4. Allow scrolling inside of an area of 200 x 200 units (for now).
In the future, it should be possible to go to infinity.
