Add support for no_std + alloc

[joshwd36]

I'm looking to use this in a no_std + alloc environment and so it would be really helpful to allow that. I've implemented this by having a std feature that is enabled by default, so it shouldn't affect existing users. The only thing the library uses that isn't available in core or alloc is the error trait, and a few println!s in tests.

[coveralls]

Pull Request Test Coverage Report for Build 457813297

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 7 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.8%) to 92.178%

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Files with Coverage Reduction	New Missed Lines	%
src/parser.rs	7	88.39%

Totals
Change from base Build 449512338:	0.8%
Covered Lines:	4855
Relevant Lines:	5267

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💛 - Coveralls

[joshwd36]

The failed clippy lints seem to be elsewhere in the code, so I'll fix them in a separate PR.

[Dandandan]

Interesting @joshwd36 ! Will try to look at this soon. I am curious what you are planning to use it for :)

[joshwd36]

I am curious what you are planning to use it for :)

I'm hoping to write a basic database engine for a unikernel OS, that doesn't have std (yet, although I may work on that), but is still functional, and wouldn't be used on the low-power devices that would normally be associated with no_std, but on hypervisors on a server.

[yjhmelody]

Is this PR still going on? Supporting no-std is great

[alamb]

As noted by @koushiro, this PR is likely superceded by #332

[joshwd36]

As noted by @koushiro, this PR is likely superceded by #332

That's fine. Should I close this now or wait for #332 to be merged?

[alamb]

Let's leave it open and I think when we merge #332 the Github API will close this one too