Spectra-lexer

-----
* Some components are now user-configurable
* More rules added (mostly orthographic variations)
* Lexer can now return incomplete matches at the cost of speed
* Various optimizations made on lexer and output components
* Minor output display bugs fixed

-----
* Program code is refactored again for better separation of components
* Most exceptions are now displayed on the main text window instead of crashing the program
* Lexer now uses the search dictionary to see if an asterisk is required because of conflicts
* Batch mode added; lexer can take input queries from a JSON dict and output all results to a file
* Standalone app can find Plover's dictionaries more easily

-----
* Program code is heavily refactored to allow easier re-use/extension
* Resources are now loaded correctly using pkg_resources (so they can be stored compressed)
* GUI for Plover plugin is no longer reset upon window close
* Text graph is displayed correctly more often
* Distribution documents and metadata are fixed

-----
* Engine no longer crashes when accessing previously closed GUI windows

-----
* Program code is completely refactored to use an event/command based message system
* Lexer processing is faster
* Text graph has wider range of colors and highlights letters more precisely
* Search is available by stroke as well as by word
* Large numbers of bugs are fixed (mostly related to text graph output)

-----
* Checks for Plover version compatibility
* Example translations are supported in steno rules
* JSON rules file extensions are renamed to indicate non-standard behavior (they contain comments)