Improve usage and help text formatting

The ansi.py module holds a collection of regular expressions
that apply automatic formatting to usage and help text with
standard syntax.

This change addresses the following:

• Section headers are generic match on capitalized word at the
  start of a line ending in a colon, instead of only matching
  on a list of magic words.
• Metavars (e.g., FILE, ADDR, PORT) are matched on any all-caps
  word not contained by quotes, not preceded by dash; instead of
  being a reserved list of magic words.
• Match any 4+ character word contained by angle brackets
  instead of reserved list of magic words.
• Add small list of special list of reserved resources, including
  localhost, stdin, stdout, and stderr.
• Fix option pattern to include stacked single letter options.
• Fix digit matching to include decimals, this also makes IP
  addresses match like numbers (naive but works).
• Add to digit matching suffixes for count (K, M, G, T) along
  with optional 'b' for bytes, case insensitive.