Add Schwab bank mapping, LEDGERBAL tag support, MS Money compatible output

[tstabrawa]

This PR adds the ability to convert CSV files downloaded from Charles Schwab checking accounts to OFX files supported by MS Money.

For convenience, I broke the changes down into the following logically-distinct commits:

• Ignore vim temp files
• Add option for MS Money compatible output
  • Deal with MS Money idiosyncrasies RE: OFX formatting
  • MS Money specific OFX header
  • Provide dummy value for TRNUID
  • Don't include blank CHECKNUM
  • Limit payee length to 32 chars
  • Use noon for dates lacking a time (Recommended by MS Money troubleshooting OFX guide)
• Include LEDGERBAL in non-split OFX output if possible
  • These are required fields per OFX spec & their absence breaks MS Money import.
• Add mapping for Charles Schwab Bank
• Add tests for ending balance analysis
• Update example --help output

Confirmed no new errors from manage lint. Confirmed all manage test tests pass.

Tested with >18 months of real-world data and manually verified transaction sanity in MS Money.

(Please let me know if anything doesn't meet coding standards, etc. Unfortunately, I'm not a native Python speaker. 😃)