Keep Medline textkeys variable internal to parser.

This is a partial revert - see discussion on pull request #355, this
list is only those keys which we merge into one string after parsing.
Remove Python 2.5 hack
initial commit for lazy-load feature branch, added stub for _lazy.py in SeqIO package

Added descriptions to the stub and fixed docstring compliance with PEP257 as well as other formatting issues.
added some dummy kwargs to read and parse for evenutal use with _lazy.py
began the process of making SeqRecordProxy
a broken test runner
still broken test
major refactoring of lazy loading base class to strip all getters and setters, new test options for __main__
further differentiation between base class and test class
an unsaved change, same as last commit
Stronger handling of lazy sequence prpoperty, unit tests are beginning to pass
additional tests passing, read light repr method
additional tests, read light __repr__ method
ported over interval-tree data structure and unit tests
changed testing to outside of module, still in non-perm. place outside of test directory to aid faster testing
added as_handle_binary() to mediate context based usage of binary files
Began work on actual fasta parsing logic
creating fasta lazy loading bindings of lazyloadproxy
unit tests beginning to work
FastaLazyLoad passing basic functionality unit tests, 3-line bug still present