Better Number Support for Mapping Migration Classes to Filenames

[robmorgan]

e.g. 'LimitResourceNamesTo30Chars' should map to '/^\d{14}_limit_resource_names_to_30_chars.php$/' instead of '/^\d{14}_limit_resource_names_to30_chars.php$/'.

[robmorgan]

This would require not splitting on individual integers, but rather splitting on number groups e.g. 'to_30_chars' instead of 'to_3_0_chars'.

[robmorgan]

wont fix.