Add character-level rotate support

[hanfeisun]

A possible solution for this issue:
#30

Demo can be previewed at:
http://hanfeisun.github.io/Leaflet.TextPath/

[leplatrem]

This is great ! Thank you !

Would you mind adding a mention in the readme to expose the feature ?

[leplatrem]

Thanks !

@fredericbonifas from my side, it looks ok to merge

[leplatrem]

I hadn't seen that @kirkau had implemented something similar. Maybe we can merge both into one rotate option.

The solution is different though :)

[fredericbonifas]

Thanks for this PR. I don't know yet how to name this option as a rotate option is already available. For now, you proposal can be implemented using the attributes option:

attributes: {
    "style": "writing-mode: tb-rl; glyph-orientation-vertical: 180;"
}

[hanfeisun]

@fredericbonifas I agree it can be implemented in the attribute, but that may look a bit intricate. There is no rotate option currently but only an option called orientation, which is "word-level rotate" instead of "character-level rotate"..

[mabhub]

Rotation of text is now possible through orientation option.

Please share any additional comments you may have.