* add extract method parameter
* change fancy to sqlnk
* test for invalid extract_method value
* test easy dbscan
* pep8
* add extract_sqlnk
* mention which parameter is used for which extact method
* add tests for extract methods with no params given
* Add the reference for the SQLNK method.
* make extract_optics_dbscan and extract_optics_sqlnk public
* fix references, sync docstrings
* fix more morege conflicts
* reorganize the code and get it closer to what we want
* pep8
* remove sqlnk, make compute_optics_graph public
* pep8
* remove unused reference
* make tests pass
* fix docstrings
* fix removal of removed parameter
* add back min_cluster size, xi needs it
* pep8
* fix docstring issue
* address Hanmin's comments
* remove core_sample_indices_
* fix comment
* pep8
* apply comments, remove example
* add public functions to classes.rst and __init__
* address Joel's comments
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