Extracted filter function from `separate-filters`

* src/midje/parsing/other/arglists.clj:
  - Moved filter function from `separate-filters` to
  `desired-fact-predicate-from`.
* src/midje/repl.clj:
  - Updated `let` bindings to use the new function.
* test/midje/parsing/other/t_arglists.clj:
  - Updated tests
has checker supports regexs
Merge pull request #177 from josephwilk/master

has checker supports regexs
Merge pull request #176 from giorgio-v/separate-filters

Extracted filter function from `separate-filters`
Setup/teardown documentation (examples from wiki) 

Added repl-background as a more intention-revealing version of `background`.
Add metadata to default filter functions
Added `with-state-changes` and `prerequisites` synonyms
Rename
This should fix issue #161
Better examples for `prerequisites`
Show type hints on failed matches when they are of different type.
When comparing two data structures who's string representation are the same, showing the type can help provide a hint as to why the test may fail.
More documentation tests for prerequisites
Fix clojure.test filename problem - #180
Removing random bad character.
Certain mis-types are more interesting than others.
Its common to use a string => regex pattern in a fact. Its not useful to know the types if this fails, so suppress it.
Refactor: Record types of failed matches as notes.
Store types of mismatched equality checks and print them during emmission.
Print namespaces for test failures
Check the namespace appears in the fact output.
A little more space between the file and namespace
Bump version to 1.5-beta2