Implemented new castep parser

=

-============================= test session starts ==============================
-platform darwin -- Python 3.7.7, pytest-3.10.0, py-1.10.0, pluggy-0.13.1 -- /Users/markus/Documents/Projects/nomad-fairdi/.pyenv/bin/python
-cachedir: .pytest_cache
-rootdir: /Users/markus/Documents/Projects/nomad-fairdi/tests, inifile: pytest.ini
-plugins: celery-4.4.7, cov-2.7.1, timeout-1.4.2
-collecting ... 
-========================= no tests ran in 0.01 seconds =========================

castep @ a7621e8c

-Subproject commit d1c8f9640a80b79656067f468db7955a18783883
+Subproject commit a7621e8cff25ad5db91df349423b1d0f5059ed62

nomad/parsing/parsers.py

@@ -44,6 +44,7 @@ from orcaparser import OrcaParser
 from cp2kparser import CP2KParser
 from fhivibesparser import FHIVibesParser
 from turbomoleparser import TurbomoleParser
+from castepparser import CastepParser
 
 try:
     # these packages are not available without parsing extra, which is ok, if the
@@ -212,11 +213,7 @@ parsers = [
     GaussianParser(),
     AbinitParser(),
     OrcaParser(),
-    LegacyParser(
-        name='parsers/castep', code_name='CASTEP', code_homepage='http://www.castep.org/',
-        parser_class_name='castepparser.CastepParser',
-        mainfile_contents_re=(r'\s\|\s*CCC\s*AA\s*SSS\s*TTTTT\s*EEEEE\s*PPPP\s*\|\s*')
-    ),
+    CastepParser(),
     LegacyParser(
         name='parsers/dl-poly', code_name='DL_POLY', code_homepage='https://www.scd.stfc.ac.uk/Pages/DL_POLY.aspx',
         parser_class_name='dlpolyparser.DlPolyParserWrapper',