Optimize polygon paint algorithm for less tool lifts.

[Juan Pablo Caram]

When given a list of paths, the current paint algorithms will lift the tool to travel to the beginning of the next path. This might not be necessary and should be evaluated for each new path.

[Juan Pablo Caram]

The method Geometry.paint_connect() was introduced to optimize tool lifts. It functions correctly but it is very slow. It is part of the seed-based copper clearing algorithm at this point.

[Juan Pablo Caram]

Speed optimization in commit 17a3316 makes it acceptable.

Now make it part of the standard paint algorithm (only in seed-based at this time).

[Juan Pablo Caram]

Added paint_connect() to the standard algorithm.

[Juan Pablo Caram]

Added paint_connect to standard paint algorithm. Resolves issue #103.

→ <<cset 41e63c439043>>