Darjeeling

* added `__contains__` to Localization
* added `reads` set to snippets
* implemented scope checking in transformation search
* implemented ability to eagerly compute transformation space
* fixed bug that caused an incorrect test ordering

* added `line_col_offset` to ProgramSourceManager
* implemented support for Rooibos transformations
* implemented time-based test ordering
* fixed bug in localization that caused an IndexError exception
* refined logging verbosity
* added new ways to construct Localization objects
* added Kaskara integration
* added basic support for insertion points
* refactored transformation generators to be faster and to use less memory

* added optional limit on number of candidate patches that may be evaluated during search.
* implemented test case reduction via the use of coverage information.
* added serialisation methods to snippet database.
* updated snippet database to record all occurrences of a given snippet.

* updated BugZoo and Boggart versions to v2.1.11 and v0.1.8, respectively.