This included removing some internal version constraints. It would be
nice if package A could say "use B@2.0.0" (when both have changed), but
when they're both in the release, we need to make a release that has a
B@2.0.0-rc in it, which doesn't match that constraint. Fortunately,
constraints aren't necessary within a release anyway.
You can still include them on the client, but they don’t work in
Safari 4 and IE 8 because semver.js uses ES 5 methods including
String#trim, Array#map/filter/forEach, and possibly others.
This should fix any unit test failures in these packages.
This is a breaking change to package-version-parser.
A PackageConstraint used to look like this:
```
{ name: String,
constraintString: String,
constraints: [{version: String|null,
type: String}]}
```
Now it looks like this:
```
{ name: String,
constraintString: String,
vConstraint: {
raw: String,
alternatives: [{versionString: String|null,
type: String}]}}
```
Where (vConstraint instanceof VersionConstraint) and
(vConstraint.raw === constraintString).
This achieves several desirable changes at once.
* `constraint.constraints` for the disjuncts in “1.0.0||2.0.0”
was confusing. `alternatives` is better.
* Having a class for VersionConstraint will come in handy because
we can add methods to it, and we can use it in the constraint
solver to represent the problem statement.
* The names “vConstraint” and “versionString” are a little verbose,
but there really shouldn’t be a lot of code that dives into this
structure, and I really wanted to avoid anyone ever writing:
`constraint.constraint.alternatives[0].version`, and then wondering
what sort of object that was (not a parsed PackageVersion! we could
parse eagerly but that might be slow).
Despite the name “package-version-parser,” PVP didn’t really provide a way to parse a package version. With this change, if you want to get the minor version of “1.2.3_4”, for example, you can just write `PV.parse(“1.2.3_4”).minor`. This simplifies the internals of PVP as well.
When you parse a version, you now get an instance of PackageVersion with a documented set of fields.
Also, make PVP work on the client. When called directly from the tool, semver is loaded the same way as before. When PVP is used as a package, it uses a copy of semver v4.1.0 kept inside the package.
This change is intended to be 100% behavior-preserving.
