Basic csv-writing capability
Initial parser unit tests (WIP)
Basic tests for data integrity in parser.records
Merge branch 'feature/parser_tests' into dev

Basic tests for integrity of parsed CODATA records.
Uncouple writer module from parser module
Slight restructuring, main is now the access point.
Tweaked the __main__ code to print one constant per line
Made CODATA a dict (order can be retained via sorted)
Basic substring search
Added a method for finding constants matching sequence of strings
Removed sequence of constants from initialisation
Removed unnecessary intermediate variable and uncommented writer init
Unix executable to launch main.py
Added subset property, contents of which to be passed to writer
Added write method, calls the writer's write method
Added a simple CSV writer (STDOUT only atm)
Added some simple CLI option-parsing
Rudimentary CLI, altered string-finding mechanism for encapsulation
Added a CODATA version CLI option
Merge branch 'feature/interface' into dev

Basic CLI with support for string-matching, format selection and
CODATA version selection included.