Better income type guessing

[redstreet]

Income type fields seem to be used inconsistently by institutions. We can still try to guess where possible.

From #41 (comment)

With a version of investments.py that includes the changes discussed here. I also very lightly modified the provided fidelity class to look like this:

class Importer(investments.Importer, ofxreader.Importer):
    IMPORTER_NAME = 'Fidelity Net Benefits / Fidelity Investments OFX'

    def custom_init(self):
        self.max_rounding_error = 0.14
        self.filename_pattern_def = '.*fidelity'
        self.get_ticker_info = self.get_ticker_info_from_id
        self.get_payee = lambda ot: ot.memo.split(";", 1)[0] if ';' in ot.memo else ot.memo

    def security_narration(self, ot):
        ticker, ticker_long_name = self.get_ticker_info(ot.security)
        return f"[{ticker}]"

    def file_name(self, file):
        return 'fidelity-{}-{}'.format(self.config['account_number'], ntpath.basename(file.name))

    def get_target_acct_custom(self, transaction, ticker=None):
        if transaction.memo.startswith("CONTRIBUTION"):
            return self.config['transfer']
        if transaction.memo.startswith("FEES"):
            return self.config['fees']
        elif transaction.type == 'income' and getattr(transaction, 'income_type', None) == 'DIV':
            return self.target_account_map.get('dividends', None)
        elif getattr(transaction, 'income_type', None) == "CGLONG":
            return self.target_account_map.get('capgainsd_lt', None)
        elif getattr(transaction, 'income_type', None) == "CGSHORT":
            return self.target_account_map.get('capgainsd_st', None)
        else:
            return None

The issue I ran into was that CGLONG and CGSHORT distributions were showing up in the OFX with a transaction.type of income, and then would be classified as dividends based on this code in investments.py:

def get_target_acct(self, transaction, ticker):
        target = self.get_target_acct_custom(transaction, ticker)
        if target:
            return target
        if transaction.type == 'income' and getattr(transaction, 'income_type', None) == 'DIV':
            return self.target_account_map.get('dividends', None)
        return self.target_account_map.get(transaction.type, None)