Fix description.
Add a auto switching coordinate feature.
Fix when the rectangular coordinates removes the default coordinate's axies labels issue.
Draft version of the auto switching coordinate feature was done.
Fix description text in the auto mode example page.
Improve coordinate plugin's default coordinate to handle axes ratio.
Eliminate the margins from canvas edge to grid in rectangular coordinate and show extra spaces in default coordinate.
Delete 2 unused files.
Add 'src/' from commit '6cdd58f79dba0b0b790e4e051abf7887f2985f8f'

git-subtree-dir: src
git-subtree-mainline: 3aef0955da90fae4a7933c6dccffcd3fb91b74a1
git-subtree-split: 6cdd58f79dba0b0b790e4e051abf7887f2985f8f