Add script for preprocessing before doc-build

The MATLAB-extension for Sphinx runs into an infinite loop if a class
contains an enumeration definition. The implemented python parser script
comments out all enumerations (a reverse function is also implemented).
In a future release, a release-script will automate the calls of
preprocess(), make html and postprocess().

docs/process.py

+#!/usr/bin/python3
+
+import os
+from os import close, remove
+from tempfile import mkstemp
+from shutil import move
+
+def preprocess():
+    """Preprocesses data for building documentation
+
+    The MATLAB Sphinx extension takes veeery (or even infinitely?) long
+    to build the documentation if a class contains an enumeration.
+    """
+
+    code_dir = os.path.abspath('../source')
+    files = _matlab_files(os.listdir(code_dir))
+    
+    n_files = len(files)
+    for n, file_name in enumerate(files):
+        print("Preprocessing file {0} [{1}|{2}]".format(file_name, n+1, n_files))
+        try:
+            fh, abs_path = mkstemp()
+            with open(code_dir + "/" + file_name, 'r') as f:
+                with open(abs_path, 'w') as ftemp: 
+                    content = f.readlines()
+                    if content[0] == '%TEMP-FILE FOR BUILDING DOCUMENTATION\n':
+                        raise RuntimeError('Found already preprocessed file.')
+
+                    try:
+                        for i, line in enumerate(content):  # Worst runtime ever 
+                            if _ignore_line(line) is False and 'enumeration' in line:
+                                ftemp.write('%TEMP-FILE FOR BUILDING DOCUMENTATION\n')
+                                _write_lines(content[:i], ftemp)
+                                for j, enum_line in enumerate(content[i:]):
+                                   ftemp.write(" %"+enum_line)
+                                   if " end" in enum_line or "end\n" == enum_line:		
+                                        _write_lines(content[i+1+j:], ftemp)
+                                        close(fh)
+                                        remove(code_dir + "/" + file_name)
+                                        move(abs_path, code_dir + "/" + file_name)
+                                        # At this point, entire file has been processed: continue outer loop
+                                        # Hackily implemented by raising an exception
+                                        raise StopIteration  
+                    except StopIteration:
+                        continue
+        except IOError:
+            pass
+
+def postprocess():
+    code_dir = os.path.abspath('../source')
+    files = _matlab_files(os.listdir(code_dir))
+    
+    n_files = len(files)
+    for n, file_name in enumerate(files):
+        print("Postprocessing file {0} [{1}|{2}]".format(file_name, n+1, n_files))
+        try:
+            fh, abs_path = mkstemp()
+            with open(code_dir + "/" + file_name, 'r') as f:
+                with open(abs_path, 'w') as ftemp: 
+                    content = f.readlines()
+                    if content[0] != '%TEMP-FILE FOR BUILDING DOCUMENTATION\n':
+                        continue
+                    try:
+                        for i, line in enumerate(content):  # Worst runtime ever
+                            if 'enumeration' in line:
+                                _write_lines(content[1:i], ftemp)
+                                for j, enum_line in enumerate(content[i:]):
+                                   ftemp.write(enum_line.replace(' %', '', 1))
+                                   if " end" in enum_line or "end\n" == enum_line:
+                                        _write_lines(content[i+1+j:], ftemp)
+                                        close(fh)
+                                        remove(code_dir + "/" + file_name)
+                                        move(abs_path, code_dir + "/" + file_name)
+                                        # At this point, entire file has been processed: continue outer loop
+                                        # Hackily implemented by raising an exception
+                                        raise StopIteration 
+                    except StopIteration:
+                        continue
+        except IOError:
+            pass
+         
+def _ignore_line(line) -> bool:
+    return (line.startswith('%') or line == '\n' or line == '')
+
+def _write_lines(lines, f):
+    for line in lines:
+        f.write(line)
+
+def _matlab_files(files) -> list:
+    return [f for f in files if (f.endswith(".m") and "_" not in f and "proto" not in f)]