Improve parsing of voteview files, including a number of date formats.

Improve parsing for the following date formats (and formatting errors):
- JAN. 1, 1900
- JANUARY 1, 1900
- JAN 1, 1900
- JAN. 1,1900
- JANUARY 1,1900
- JANUARY. 1, 1900
- JAN, 1, 1900
- JANUARY, 1, 1900
- JAN.1, 1900

(This also includes allowing SEPT for September.)

In addition, it handles an extraneous counter in the 7th House and the use of a digit to disambiguate the two Burdicks in the 102nd Senate. It also checks for the presence of a description so that an anonymous rollcall doesn't kill the whole file.