Add a from_str function that calls out to the associated method on the trait
Add from_str docs
Remove the __log function for __log_level

Also redefine all of the standard logging macros to use more rust code instead
of custom LLVM translation code. This makes them a bit easier to understand, but
also more flexibile for future types of logging.

Additionally, this commit removes the LogType language item in preparation for
changing how logging is performed.
Generate random BigUints and BigInts
Fix glitches with struct field aligned indents
test the correct function (oops)
Indent correctly after opening square bracket
Allow indenting to align struct fields after curly brace
Indent return type to align with arguments
Add custom group for rust-mode
Add paragraph fill and auto-fill for multi-line comments
Add ERT tests
Fix Acceptor iterator ending early if a connection attempt fails
Forgot to make accept() home for IO
Make I/O tests use run_in_mt_newsched_task to get more multi-threaded test coverage
Incorporate feedback from huonw

- use identifiers with underscores to avoid unused variable warning
- implement on R: Rng instead of on R: RngUtil
- bugfix: zero BigInts were being generated twice as often as any
  other number
- test that gen_biguint(0) always returns zero
Fix regression of multi-line statement indents
Cover all cases for padding in paragraph fills as intended
Remove even more usage of clownshoes in symbols

This removes another large chunk of this odd 'clownshoes' identifier showing up
in symbol names. These all originated from external crates because the encoded
items were encoded independently of the paths calculated in ast_map. The
encoding of these paths now uses the helper function in ast_map to calculate the
"pretty name" for an impl block.

Unfortunately there is still no information about generics in the symbol name,
but it's certainly vastly better than before

    hash::__extensions__::write::_version::v0.8

becomes

    hash::Writer$SipState::write::hversion::v0.8

This also fixes bugs in which lots of methods would show up as `meth_XXX`, they
now only show up as `meth` and throw some extra characters onto the version
string.
Update for_expr docs.