support html past (e.g., jupyter notebook, QUIP)

[xychang]

Hi Ganessh,
Really appreciate it that you have created this awesome plugin. Personally, I work with some tools (e.g., jupyter notebook, QUIP) that doesn't have very good raw text when copying tables, so to get proper table content, I need to refer to the html paste.
Here is a draft diff that solves my problem and I hope is can also help other who have similar issues.
Best Regards

[xychang]

Here are some example raw text I got for your reference:
from quip
\nCOL_NAME_A\t\nCOL_NAME_B\n\nCONTENT_A\t\nCONTENT_B\n

from jupyter notebook
COL_NAME_A\nCOL_NAME_B\nCONTENT_A\nCONTENT_B