Improve wl:command syntax with substring matching

[idpaterson]

It is not particularly convenient to fully type out wl:search something to find tasks. Version 0.6 adds at least three more handlers, so this needs to be improved. Here is the current state of command routing in the workflow:

• The colon (:) character was chosen arbitrarily
• The colon character requires pressing the Shift key, which is not convenient
• After typing wl:search, one might attempt Option+delete to get back to wl:, but this does not work since the colon does not break the word
• Handlers are selected by exact match against the full command, including the colon character
• Attaching the command immediately after wl (i.e. no space between) avoids any conflicts with task entry

After improvements:

• The separator will be optional and any non-word character can be used (e.g. wl.search, wlsearch)
• The workflow will use a hyphen (-) for autocompletion (e.g. wl-task 28713804)
• The hyphen, should the user choose to type it, does not require pressing the Shift key
• After typing a command like wl-search, Option+delete will get you back to wl- ready for the next command
• When a command is provided, the first matching handler will be used, allowing a single letter to represent a command
• I will attempt to keep naming of commonly-used commands distinct, for example wl-due rather than wl-today since the latter would conflict with wl-task when the user types wlt. wld will be the quickest way to see tasks due today
• The command must still be attached immediately after wl

[idpaterson]

This has been implemented as described above in the 0.6.0-alpha releases.