Add support for Bitbucket style header IDs

[bravoecho]

No description provided.

[mzlogin]

Thx for your PR!

Have you found the source code which BitBucket used to generate toc ids? Without that, it's hard to judge the rule you wrote is right or not.

Besides, I noticed that all Chinese Characters in headers are gone in BitBucket generated toc ids, that's different from GFM.

[vanildosouto]

Thx for your PR!

Have you found the source code which BitBucket used to generate toc ids? Without that, it's hard to judge the rule you wrote is right or not.

Besides, I noticed that all Chinese Characters in headers are gone in BitBucket generated toc ids, that's different from GFM.

In the link (https://bitbucket.org/tutorials/markdowndemo/src/master/README.md) have a example to link markdown style from Bitbucket

[mzlogin]

@vanildosouto yes, but sadly it has not mentioned the rules to generate toc ids.