Convert the decimal separator of numbers

It use two option, one declaring the what separator is used in csv, the
other in ledger. If both or none are set, no conversion is
needed. Otherwise a conversion is needed.
Merge pull request #61 from vanicat/t/comma-digit

Convert the decimal separator of numbers
Prevent crash when realine.__doc__ is None.
Update README to include windows information.
Strip non-number characters from amount column

Remove any characters which are not digits 0-9, minus "-" or the
decimal separator "." or ",".

This is necessary if the CSV input contains plus signs for positive
amounts, thousands separators or currency symbols, which should not
appear in the ledger output.
Fix some README typos
Merge pull request #65 from hfs/documentation

Fix some README typos
Merge pull request #64 from hfs/number_format

Support for more number formats by removing non-number characters
Merge pull request #62 from mlamby/windows-fixes

Prevent crash when realine.__doc__ is None.
Merge pull request #63 from mlamby/patch-1

Update README to include windows information.
Load a list of accounts from an accounts file.
Added a --account-file option that will load a list of defined accounts from the specified file.
Describe the accounts-file option in the readme.
Cleanup accounts-file option documentation.
CSV reading: continue without explicit dialect upon guess failure

Rationale: the default settings of Python's csv module allow to read several
CSV sub-formats without having to specify a dialect. With this change we allow
to read them even when the CSV sniffer is unable to determine the actual
dialect in use.
Merge pull request #70 from mlamby/feature-account-list

Optionally read account definitions from a ledger file
Merge pull request #71 from zacchiro/master

CSV reading: continue without explicit dialect upon guess failure