Fix notation-vs-tab bar misalignment

[jzohrab]

Hi @0xfe / Mohit,

This PR fixes a bar misalignment mentioned in #99, and PR #120. Prior to this PR, this works (bars aligned)

tabstave notation=true key=E time=12/8
notes :w 7/4 | 6/5

But this breaks (bars misaligned)

tabstave notation=true key=E time=12/8
notes :w 7/4 | 6/5 |

In this branch I added some very simple tests verifying the fix: code is rendered and the SVG is compared, eg:

Note that I pulled the single-line code fix from issue #99 -- I couldn't quite see why this fixed the issue, but it did! The existing tests pass.

[0xfe]

Looks good overall. Thanks for the change and for fixing the tests. Some minor comments.

[jzohrab]

Thanks @0xfe ! This will close out #99 . Cheers, jz

[0xfe]

Looks great, merging!