cleanup pio module for picoLisp.

1. The module functions have been modified to
   match the existing order of function parameters
   in a function call.

   e.g. (pio-pin-setdir *pio-output* 'PB_29)

   instead of: (pio-pin-setdir 'PB_29 *pio-output*)

2. cleanup/fix comment typos for picoLisp's pors
   operations.
Rewrite plisp_term_getchar() to use internal symbols.

1. Remove conditional blocks for other languages which
   are empty. (We'll put them back when we get to the
   actual implementation).

   This is possible only because all languages are now
   first value citizens. The code looks a bit cleaner
   now.

2. Beautify comment section in src/picolisp/tab.c
Fix typo and add comment.