Add failing test for imported mixin with wrong path

When relative URLs are on, and there's an image referenced via url(...),
if the URL is unquoted, the generated CSS duplicates the base path
1.5.0 release
fixed mixin call matching for multi-selector parent...
a few minor selector match fixes...
a few minor selector match fixes: updated tests.
Add visitor.js array-based function cache for faster lookups. perf / #1615
Optimize visitor.visitArray() for perf. #1615
Misc. perf optimizations. #1615
New input chunker in parser.js. #1615
Minor fixes. #1615
update bower.json main script

for bump 1.4.2 -> 1.5.0
Avoid fs.statSync unless env.syncImports is specified.
Check location.port for truthiness

According to the w3 spec for Window:

http://www.w3.org/TR/Window/#location

`location.port` might be null. This PR checks that it is truthy before checking for the port's length.

One place where location.port is null is within [jsdom](https://github.com/tmpvar/jsdom), so if you run less within Node, within jsdom, it throws an exception in this code.
Merge pull request #1628 from tomfuertes/patch-1

update bower.json main script
Support specifying custom variables when calling lessc and less.js.

Both lessc and less.js can now be provided with global variables that
all .less files will have immediate access to. This can be used to
provide, for example, a base path for an @import, signed URLs offering
temporary access to an image on S3, or anything else.

lessc has two new parameters, --global-var and --modify-var. Both take
a value of the form "varname=value". --global-var declares variables
immediately before the content of the .less files, and --modify-var
declares them after.

--global-var is used when rules, imports, or other variables will depend
on the provided variable.

--modify-var is used to override a variable declared within the .less
file.

less.js's equivalent for global variables is less.globalVars. This can
be set before loading less.js. There is no new requivalent to
--modify-var, as less.modifyVars can be used for that purpose.
Merge pull request #1655 from chipx86/custom-vars

Support specifying custom variables when calling lessc and less.js.
Merge pull request #1643 from matthewp/location-port

Check location.port for truthiness
Fixes #1619
Merge branch 'selector-match-fixes' of https://github.com/seven-phases-max/less.js
Change lessc exit status code on error. Fixes #1637