first stab at generalizing gpointers to handle gobjs
more work on pointers for gobjs, plus a "find" method for canvases
* removed and renamed some methods for *info objects
* properly escaped "boxtext" output
* output expanded args for canvasinfo "args"
Updated documentation for *info classes
Merge branch 'gpointer/generalize'
This change allows gobjs to be pointed to by gpointers.  This makes it
possible to improve the interface for the *info objects, as they can pass
around lists of gpointers to refer to objects/canvases.  This is better than
using index numbers and canvas levels, which is cumbersome and in some cases
much slower (since a walk through the glist is required each time to find
the referrent for an index).