Make command line parsing actually work.

Support three types of arguments;

 Booleans
   --vhdl-upper-case-types
   --no-vhdl-upper-case-types

 Integers
   --vhdl-basic-offset=20

 Strings
   --xxx=abc
   --xxx='abc 123'
   --xxx=abc=123

Search the `vhdl-mode/vhdl-mode.el` and `macs-verilog-mode/verilog-mode.el` for
`(defvar` to find the arguments you can customize.