[Mailman-Developers] [CLI Project] Switched command Parsing to YACC and LEX

[Rajeev S]

Hi,

As mentioned, I have pushed r67, that comprises of the improved command 
parsing system using Lex and YACC, for the Mailman shell.
The PLY module is used for the purpose.

Every command has a parser script associated with it, under the 
`client/parsers/` directory. The parser is imported and used by each command
independently. The parser returns the necessary arguments as a hash 
table, which can be easily used by the command execution
procedure.

The change of command parsing method to PLY now handles both command 
validation and parsing/processing, which was
previously done in independent command processing steps. The r67 also 
improves the environment variable management.

http://bazaar.launchpad.net/~rajeevs1992/mailman.client/mailmancli/revision/67