Document how compilers and minifiers are going to work

--HG--
branch : wosc-compilers
Extract common registry code, so we can reuse it for CompilerRegistry

--HG--
branch : wosc-compilers
Implement basic structure of compiling

* Registry for compilers and minifiers
* Configure comiler/minifier on Resource
* Call compilers during render() if enabled by configuration option

--HG--
branch : wosc-compilers
Implement determining source and target filenames for compilation

--HG--
branch : wosc-compilers
Add name attribute to Compiler base class

--HG--
branch : wosc-compilers
Change test helper to use instance instead of class, so we can manipulate the compiler per test

--HG--
branch : wosc-compilers
Adapt file existence checking to account for compilers

--HG--
branch : wosc-compilers
Make minifiers work

While it is somewhat attractive to try and pass the minifier to the
minified Resource object as its compiler, that would necessitate for
the compiler to be able to change the resource's filename, which is
kludgy.

Thus, the clear separation between Compiler and Minifier we have now
is deemed more attractive, especially since a) the current code in
Resource is not too kludgy and b) we would need the mode_parent anyway
(since the parent might have to be compiled before minifying).

--HG--
branch : wosc-compilers
Implement compilers that call external commands

--HG--
branch : wosc-compilers
Require current py.test version so we can use @pytest.fixture

--HG--
branch : wosc-compilers
Implement compilers that use a third-party python package

--HG--
branch : wosc-compilers
Use entrypoints to find compilers in tests, so that we actually register them correctly

--HG--
branch : wosc-compilers
wording

--HG--
branch : wosc-compilers
Allow configuring compilers and minifiers on Library level, with override on Resource level

--HG--
branch : wosc-compilers
Document compiler API

--HG--
branch : wosc-compilers
Document pre-packaged compilers

--HG--
branch : wosc-compilers
Implement command-line program to force compilation of resources

--HG--
branch : wosc-compilers
Fix Python-3 compatibility: the HTML content is a bytestring (per PEP-3333), so we need to treat it as such
Restore Python-2.6 compatibility (where argparse is not in the stdlib yet)

--HG--
branch : wosc-compilers
Merge default

--HG--
branch : wosc-compilers