Adds using statement to the one and only true index.
Adds docstrings to lines() iterators.
Adds note about procs and multiple variable assignment.
Adds note about iterators having same signature as procs.
Documents wrapping named arguments in curly braces.
Adds parseopt2 module to documentation index.
Moves mongodb module to lower level wrapper group.
Removes links to modules recently removed from stdlib.
Documents rstgen index related procs.
Duplicates string literal table for character literals.

Hopefully the index spamming will lead more people here.
Adds note about conflicts with using as a statement.
Clarifies system.lines() docstring.

Amends 4dc22e5f7cacd86bf49b7fd9e51346b5e4758e77.
References TRune, links unicode modules where mentioned.

Amends 9ee10e5cdb9b2bb90fd40842c59f04513bacd9e6.
Merge pull request #817 from gradha/pr_improves_docs2

Improves docs2