Fixed a typo that prevented building on OS/X.
The pdytools module now checks for Python v2.7 rather than v2.6.
Define SOABI when dynamic loading is enabled.
The directory containing the executable is now derived from sys.executable
(rather than argv[0]).
Added support for dynamically loading extension modules that are installed
adjacent to the application executable.
The sip module can now be explicitly included if required.
Documented the support for adjacent extension modules.
emove the VERSION file and read the version information from version.py
instead.  setup.py will now create a minimal version.py if needed.  This should
allow 'pip install -e ...' to be used from the hg repo (although the version
information won't be valid).