LICENSE: Migrate from MIT to Apache 2.0 license

Adopt Apache 2.0 license in order to have uniform licenses across Quick
and Nimble.
Merge pull request #167 from modocache/apache-license

LICENSE: Migrate from MIT to Apache 2.0 license
Adds Nimble to Target Dependencies for Quick tests.

Without this, compiler failures can sometimes occur with out-of-date or
unbuilt Nimble frameworks.
Merge pull request #179 from jeffh/nimble-dependency-for-quick-tests

Adds Nimble to Target Dependencies for Quick tests.
Refactor qck_ macros into functions
Rename Objective-C it/itBehavesLike methods

Avoids conflicts with the `it` and `itBehavesLike` macros.
Unfortunately, using QUICK_DISABLE_SHORT_SYNTAX doesn’t help here,
since consumers will probably (intentionally or not) import the
World+DSL header in Objective-C.
Refactor macro aliases as static inline functions

This avoids naive text replacement when the keywords are encountered in
(say) method parameter names.

Unfortunately, it doesn’t seem to be possible to do this for `it` and
`itBehavesLike` if we want to preserve file/line information.
Add newline to itBehavesLike test, for breakpoints
Fix tabs -> spaces
Rename void block typedef to QCKDSLEmptyBlock
Clarify what might conflict with shorthand syntax
Merge pull request #185 from github/fix-objc-breakpoints

Fix breakpoints in Objective-C
README: Test target must contain one Swift file

Fixes #164.
ExampleGroup: "root example group" not in name

Fixes #168. Like, for realsies this time (unlike #169).

Also fix access control and add documentation to a variety of Example
and ExampleGroup classes and methods.
ExampleGroup: fix access control, add docblocks

ExampleGroup methods were undocumented, and did not have any access
modifiers specified. Add documentation and more granular access control.
NSException+Callsite: Remove obsolete file

NSException extension was no longer used.
Callsite: Add documentation, access control
ExampleMetadata: Add documentation, access control
World: Do not subclass NSObject
World: Add documentation, granular access control

Remove World+Singleton.swift, and instead make World's initializer
private.