fix!: Parsing over a slice should invoke complete parsers

[epage]

Under the original nom design, users could mix and match complete/streaming parsers as needed. Now, they can't. This restores that ability by modifying the stream. As part of that, we apply this to two existing parsers, length_value and Parser::and_then

The problem is this comes with a 30% performance hit for partial parsing because we increased the size of the Stream (I benchmarked with is_partial returning a static value and no change). See #72 for fixing that.

Despite the performance degradation, I'm going to merge this as this is necessary functionality for parsers to work correctly and we have #72 for improving the performance.

[coveralls]

Pull Request Test Coverage Report for Build 4196969852

• 26 of 65 (40.0%) changed or added relevant lines in 3 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.2%) to 52.466%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/stream/mod.rs	22	61	36.07%

Files with Coverage Reduction	New Missed Lines	%
src/character/complete.rs	1	81.45%

Totals
Change from base Build 4196095385:	-0.2%
Covered Lines:	1734
Relevant Lines:	3305

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💛 - Coveralls