* Replace a single-character string literal with a character literal.
* Use is_some() instead of comparing with Some(_).
* Add code-quotes around type names in comments.
* Use !...is_empty() instead of len() != 0.
* Tidy up redundant returns.
* Remove redundant .clone() calls.
* Remove unnecessary explicit lifetime parameters.
* Tidy up unnecessary '&'s.
* Add parens to make operator precedence explicit.
* Use debug_assert_eq instead of debug_assert with ==.
* Replace a &Vec argument with a &[...].
* Replace `a = a op b` with `a op= b`.
* Avoid unnecessary closures.
* Avoid .iter() and .iter_mut() for iterating over containers.
* Remove unneeded qualification.
All values are now references into the value table, so drop the
distinction between direct and table values. Direct values don't exist
any more.
Also remove the parser support for the 'vxNN' syntax. Only 'vNN' values
can be parsed now.
Give these crates each a more standard directory layout with sources in
a 'src' sub-sirectory and Cargo.toml in the top lib/foo directory.
Add license and description fields to each.
The build script for the cretonne crate now lives in
'lib/cretonne/build.rs' separating it from the normal library sources
under 'lib/cretonne/src'.
