PEP8 on ABINIT parser

Branch parser_abinit_PEP8 branched off from v0.9.2 an hour ago (so it's up to date with Friday's state)

The main file of the ABINIT parser

dependencies/parsers/abinit/abinitparser/parser.py

had inhomogeneous indentations, ranging from 4-, 3-, and single-space indentations; this caused problems when editing the code. The indentation was fixed using the autopep8 tool.

I ran the tests and DOS cases again and they produce the same archive outcome.

There is also a minor fix to the block of code that finds the DOS file: the parser was reporting "multiple DOS files found" when there isn't any DOS file.