Add a chroma class wrapper when in "table mode" (#63)
Add a chroma class wrapper when in "table mode" (#63)

This commits adds a div wrapper when linenumbers are formatted in table, to get the correct CSS matchers.

This commit also fixes some CSS table issues when tables are put into a larger context with other stylesheets:

* No borders.
* Overflow to fit in potentially narrower containers.

Fixes #62
alecthomas/chroma,alecthomas/chroma,alecthomas/chroma,alecthomas/chroma