feat(input): Blankt impl for all slices

[epage]

This does not help with Compare (because of ignore case) and FindSlice (memchr).

Inspired by rust-bakery/nom#1482

[coveralls]

Pull Request Test Coverage Report for Build 4068794753

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 4 of 4 (100.0%) changed or added relevant lines in 1 file are covered.
• 3 unchanged lines in 2 files lost coverage.
• Overall coverage remained the same at 58.123%

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Files with Coverage Reduction	New Missed Lines	%
src/character/complete.rs	1	81.45%
src/input.rs	2	38.81%

Totals
Change from base Build 4068732326:	0.0%
Covered Lines:	1685
Relevant Lines:	2899

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💛 - Coveralls