drop support for parallel marc versions

can still be handled by the user, but is a niche use case

env/CONFIG

@@ -1,5 +1,5 @@
 # "set"-syntax needed only for tcsh (but works with bash and zsh)
-set DAMASK_NUM_THREADS    = 4
+set DAMASK_NUM_THREADS  = 4
 
-set MSC_ROOT              = /opt/msc
-set MARC_VERSION          = 2019.1
+set MSC_ROOT            = /opt/msc
+set MARC_VERSION        = 2019.1

python/damask/_environment.py

@@ -3,7 +3,6 @@ from pathlib import Path
 
 class Environment:
 
-    # ToDo: Probably, we don't need a class (just a module with a few functions)
     def __init__(self):
         """Do Nothing."""
         pass

python/damask/solver/_marc.py

@@ -49,7 +49,7 @@ class Marc:
                   ):
 
 
-        usersub = damask.environment.root_dir/Path(f'src/DAMASK_marc{self.version}')
+        usersub = damask.environment.root_dir/'src/DAMASK_marc'
         usersub = usersub.parent/(usersub.name + ('.f90' if compile else '.marc'))
         if not usersub.is_file():
             raise FileNotFoundError("DAMASK4Marc ({}) '{}' not found".format(('source' if compile else 'binary'),usersub))

src/DAMASK_marc2018.1.f90

@@ -1 +0,0 @@
-DAMASK_marc.f90

src/DAMASK_marc2018.f90

@@ -1 +0,0 @@
-DAMASK_marc.f90

src/DAMASK_marc2019.1.f90

@@ -1 +0,0 @@
-DAMASK_marc.f90

src/DAMASK_marc2019.f90

@@ -1 +0,0 @@
-DAMASK_marc.f90