support dot . in file name

[bangedorrunt]

i'd like to have . support in file name, for example learn.me.some.

[srid]

To implement this, modify this function:

neuron/neuron/src/lib/Neuron/Zettelkasten/ID.hs

Lines 121 to 123 in 7140f96

	customIDParser :: Parser Text
	customIDParser = do
	fmap toText $ M.some $ M.alphaNumChar <|> M.char '_' <|> M.char '-'

And expand the test coverage.

[srid]

Dot is possibly going to be used to signify hierarchy in #379