Incorrect handling of some chords with slashes

Windows 7, GIT commit: 1132f3d

The special casing of slash for chords like C/E and also C6/9 leads to bad behavior for a number of other strings that include slashes:

/Bb
N/C
/Good
/Xylophone
C/Good
C/Xylophone

etc.

The first of the chords listed above should be treated as a recognized chord with no root or extension but a bass of Bb (and hence rendered as such). The others should be treated as being unrecognized to various degrees, with C/Good and C/Xylophone at least transposing properly.

Currently, a variety of bad things happen when entering chords like this. /Bb is not rendered well, and the others are transformed into something else.