add unit test to reproduce issue35 ($, %, &, …) as symbol constituents
allow $ % & = as characters in Symbol
also account for symbol constituents '$%&=' in scanNextToken

(This is a bit of a DRY violation: the information about which
characters may begin a token appears as case labels in scanNextToken
and as set membership in CharClassify.)
Merge branch 'feature/issue35' into develop

* feature/issue35:
  also account for symbol constituents '$%&=' in scanNextToken
  allow $ % & = as characters in Symbol
  add unit test to reproduce issue35 ($, %, &, …) as symbol constituents