We're getting segfaults in places where this isn't checked. Also, add
some asserts so we can catch bad tool push/pop.
Removes all uses of GetCommandStr() and makes it private.
Includes the addition of an onSetCursor() handler which must be called
from both the GAL canvas AND the GAL backend (at least on OSX) to prevent
cursor flickering between (for instance) pencil and arrow.
Also includes new architecture for point editors which allows them to
coordiate cursors with the editing tools (so we can switch to an arrow
when over a point).
We were running into various corner conditions where a tool's event
loop would exit while the tool was still active, or the tool would
get popped while we were still in the event loop. (A lot of these
had to do with the POINT_EDITOR's, but not all of them.)
The new architecture:
1) tools always do a Push()/Pop()
2) everyone is responsible for their own pops; no more stack-clearing
on a cancel
3) CancelInteractive events go to all tools to facilitate (2)
If a tool called something like clearSelection while processing a
MOUSE_CLICK, the SELECTION_TOOL will pass the clearSelection
COMMAND_EVENT because it handles it as a transition, not as an
event. Because m_passEvent is effectively global, the tool manager
would then interpret that as passing the MOUSE_CLICK and we'd end
up processing the click by multiple tools.
This removes the remaining hard-coded segments counts and replaces them
with the relative error calculation where the segments per arc is
determined by the maximum error we allow (smaller arcs = fewer segments)