GROOVY-6869: Move collate() and permutations() from List to Iterable
GROOVY-6920: Add disjoint, minus and toSpreadMap to Iterable

Added these methods to Iterable.
disjoint(Iterable)
minus(Object)
minus(Iterable)
toSpreadMap()

Added this method to Collection.
minus(Collection)
minor refactor (clean up imports)
Merge pull request #476 from yukoba/DisjointMinusToSpreadMap

GROOVY-6920: Add disjoint, minus and toSpreadMap to Iterable
GROOVY-6929: Fix NPE with map constructor calls and setter only
Objecct -> Object

Sorry, my mistake.
Merge pull request #479 from yukoba/patch-3

Objecct -> Object
Documentation about running one unit test

It is written here
https://github.com/groovy/groovy-core/blob/master/gradle/test.gradle#L66
but I think it is worth writing it on README.adoc.
Merge pull request #480 from yukoba/patch-4

Documentation about running one unit test
GROOVY-6933: Add swap() to List and array.
Collections.swap() returns nothing, but this method returns this object.
First bits of work around quality builds:
   * re-enabled checkstyle
   * generate HTML report
   * CodeNarc, Cobertura disabled
Upgrade to Asciidoctor Gradle plugin 0.7.3
Merge pull request #481 from yukoba/Swap

GROOVY-6933: Add swap() to List and array
merge the two font css imports into one for only one download from the remote font server
Enable CodeNarc in quality check
Added Jacoco coverage
Fixed "indy" system property leaking into Gradle build script itself
GROOVY-6915: VerifyError in markup template engine if "equals" is used instead of a semicolon
Test case for GROOVY-6939
Test case for GROOVY-6940