First usable generator source.

Still issues with usage rules and error reporting, but functional.

generator/demo/demo.yml

@@ -0,0 +1,53 @@
+---
+argspec: "dc"
+any_parameters: true
+
+argument_tokens:
+    - argument: "expression"
+      usage: "evaluates an expression"
+      short_argument: "e"
+      clean_token: "EXPRESSION"
+      has_parameters: true
+      parameters:
+          - index: 1
+            name: "expression"
+    - argument: "file"
+      usage: "evaluates the contents of a file"
+      short_argument: "f"
+      clean_token: "FILE"
+      has_parameters: true
+      parameters:
+          - index: 1
+            name: "file"
+help_token:
+    - usage: false
+      short_argument: "h"
+
+version_token:
+    - usage: false
+      short_argument: false
+
+license_token:
+    - usage: false
+      short_argument: false
+
+argument_explanation: false
+
+usage:
+    - flags:
+        - "OPTIONS"
+      positional: false
+
+usage_rules:
+    - rule_name: "OPTIONS"
+      options:
+          - option: "EXPRESSION"
+            has_next: true
+          - option: "FILE"
+
+version: "dc (GNU bc 1.07.1) 1.4.1\\n\\nCopyright 1994, 1997, 1998, 2000, 2001, 2003-2006, 2008, 2010, 2012-2017 Free Software Foundation, Inc."
+
+license: "This is free software; see the source for copying conditions.\\nThere is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, to the extent permitted by law."
+
+help_addendum: "Email bug reports to:  bug-dc@gnu.org"
+---