Improve NpmSpec parsing

[gnattishness]

Makes NpmSpec more closely match the node-semver implementation in what syntax it accepts as valid.

Resolves #115

[gnattishness]

I've left all the commits separate, but I'll squash them once you're happy with the review.
Thanks for your time!

[gnattishness]

This now splits across multiple whitespace, but also allows for newlines (so it would allow >0.1.2 \n<3.4.5)
Would it be worth raising an error at the start if the expression contains newlines?

[pombredanne]

IMHO this is not worth

[gnattishness]

I assume you're referring to "not worth raising an error for newlines", as opposed to allowing multiple spaces between the subclauses?

[pombredanne]

I assume you're referring to "not worth raising an error for newlines"

Correct. How many times are there new lines across all the package.json anyway?

[gnattishness]

Yeah I wouldn't expect it as an issue, just a slight nitpick of my own code where it's different to the current npm implementation.

[gnattishness]

I also noticed that NpmSpec would probably accept v>0.1.2 as valid.
I get that v isn't part of semver, but not sure if >v0.1.2 is preferred or neither.
Happy to add something about this in, if you have any thoughts.

[pgampe]

What is missing here? The conflict is only in the changelog and needs to be resolved before merge anyway.

[gnattishness]

@pgampe Refer to the linked issue. The maintainer is waiting on clarification from the NPM semver implementers.
If you'd like action here, I'd be happy for any progress in pushing for an answer from the NPM folks :)