Fixes #540 #544 #552 #554 #555

No functional change. Prepares for running a full alias through the
state machine.

Related to https://github.com/zsh-users/zsh-syntax-highlighting/issues/549#issuecomment-431628338 and to #556.

Update the test point for f3410c5862 (#264),
which changed the highlighting of aliases to consider what they resolve to.

Now the test file has both ${aliases[alias1]} and ${functions[alias1]},
the expectation is 'alias', and passes; thus:

Fixes #588.

The test never actually defined a function named 'alias1', not even
when zsh 5.4 warned it about this (see 9523d6d49cb3d4db5bd84c3cec6168a2057fe3ab,
which was wrong and is hereby reverted).

The test that's now failing has been filed as issue #558.

Closes #547.

Fixes #499.

Avoids an error in pre-5.0.8: bad pattern: -[]#

This could be triggered if BUFFER='\'.

No functional change.

No functional change.

() ) } are invalid as a redirection target.
() } are invalid in an array assignment.

No functional change.

This allows for use of continue.

The below code handles this case.

This will set style=alias before the great fork.

Follow-up to 2c15b0e996 ("Learn $flags_sans_arguments…").

Found by code inspection.

Follow-up to 1fee620e62.

Fixes #365.

Fixes #168.