FR: search: Take implied contexts and projects into account

[navytux]

I realized for myself that for many todo items giving only one context or label (project in topydo speak) is enough to provide complete set of contexts or labels. For example if +pygolang is one of my work projects it can automatically also mean +work, and if e.g. @jerome is my co-worker it can also automatically mean +work. There are other associations - e.g. @metroA means @incity and many similar. Thus instead of explicitly writing all set of relevant contexts and labels for every todo item, one can setup a database with such associations, and specify in todo.txt only what is essential.

A draft patch that implements such functionality is here: https://lab.nexedi.com/kirr/topydo/commit/33619796

It is used like this:

	[implied]
	# X implies -> A B C ...
	+pygolang   = +work +python +go
	+wcfs       = +work
	@jp         = +work
	@jerome     = +work +zodbtools
	...

	$ t +work	# todo itmes related to work
	$ t -+work	# todo items related to not-work

this provides a bit of start for work/life balance without explictly
marking every todo with redundant +work label or using complex queries.