Cleanup

- renamed grammar.txt to grammar.bnf

grammar.bnf

@@ -0,0 +1,69 @@
+
+This is a full BNF grammar for the task command line.  It is intended that a
+future release of task will incorporate a complete lexer/parser implementing
+this grammar.
+
+
+command:
+    VERSION
+  | HELP
+  | PROJECTS
+  | TAGS
+  | SUMMARY
+  | HISTORY
+  | NEXT
+  | CALENDAR
+  | ACTIVE
+  | OVERDUE
+  | STATS
+  | USAGE
+  | OLDEST
+  | NEWEST
+  | EXPORT <file>
+  | COLOR
+  | DELETE <id>
+  | UNDELETE <id>
+  | INFO <id>
+  | START <id>
+  | DONE <id>
+  | ADD [<tags>] [<attrs>] [<desc>]
+  | LIST [<tags>] [<attrs>] [<desc>]
+  | LONG [<tags>] [<attrs>] [<desc>]
+  | LS [<tags>] [<attrs>] [<desc>]
+  | COMPLETED [<tags>] [<attrs>] [<desc>]
+  | <id> [<tags>] [<attrs>] [<desc>]
+  | <id> <substitution>
+
+id:
+    \d+
+  | \d{8}-\d{4}-\d{4}-\d{12}
+
+tags:
+    +<tag>
+  | -<tag>
+
+tag:
+    \w+
+
+attrs:
+    <attr>
+  | <attr> <attrs>
+
+attr:
+    <name>:<value>
+
+name:
+    \w+
+
+value:
+    .+
+
+substitution:
+    / <pattern> / <pattern> /
+
+pattern:
+    .+
+
+file:
+    ?
+