font-patcher: Pull out opening and generating the font

[why]
These operations are also not strictly patching.
When we want to handle more than one font we need to have this outside
the patch() function.

[how]
Put opening and exporting (previously in __init__() and patch() into
main() outside the patcher object.

No functional change (except the sourceFont is now closed :->)

Signed-off-by: Fini Jastrow <ulf.fini.jastrow@desy.de>

font-patcher

@@ -165,10 +165,9 @@ class font_patcher:
         self.onlybitmaps = 0
         self.essential = set()
         self.config = configparser.ConfigParser(empty_lines_in_values=False, allow_no_value=True)
-        try:
-            self.sourceFont = fontforge.open(self.args.font, 1) # 1 = ("fstypepermitted",))
-        except Exception:
-            sys.exit(projectName + ": Can not open font, try to open with fontforge interactively to get more information")
+
+    def patch(self, font):
+        self.sourceFont = font
         self.setup_version()
         self.get_essential_references()
         self.setup_name_backup()
@@ -180,8 +179,6 @@ class font_patcher:
         self.sourceFont.encoding = 'UnicodeFull'  # Update the font encoding to ensure that the Unicode glyphs are available
         self.onlybitmaps = self.sourceFont.onlybitmaps  # Fetch this property before adding outlines. NOTE self.onlybitmaps initialized and never used
 
-
-    def patch(self):
         if self.args.single:
             # Force width to be equal on all glyphs to ensure the font is considered monospaced on Windows.
             # This needs to be done on all characters, as some information seems to be lost from the original font file.
@@ -1279,7 +1276,14 @@ def main():
     check_fontforge_min_version()
     args = setup_arguments()
     patcher = font_patcher(args)
-    patcher.patch()
+
+    try:
+        sourceFont = fontforge.open(args.font, 1) # 1 = ("fstypepermitted",))
+    except Exception:
+        sys.exit(projectName + ": Can not open font, try to open with fontforge interactively to get more information")
+
+    patcher.patch(sourceFont)
+
     print("\nDone with Patch Sets, generating font...\n")
     patcher.setup_font_names()
     patcher.generate()