Tidied up code using rubocop autocorrect
Changed <=> to call it's parameter 'other' not t2/d2
Updated the changelog for v 0.1.1
Deprecated ZTime#is_am?, ZDate#is_today? and
RecurrenceConstruct#get_interval in favour of #am?, #today? and #interval
Refactored RecurrenceConstruct#interval and
RecurrenceConstruct#has_interval_of? into one method

\#has_interval_of? was only being called from #interval anyway
Made RecurrenceConstruct raise errors in the standard ruby style

`raise ErrorClass, message` rather than `raise ErrorClass.new(message)`
Corrected indentation in ConstructInterpretter as suggested by rubocop
Reindented the sorting of occurrences over several lines as suggested by rubocop
Replaced perl-style global regexp variables with Regexp.last_match as
suggested by rubocop
Replaced begin...end while loop with loop do... break if... as suggested
by rubocop
Reindented occurrence as suggested by rubocop
Refactored RecurrenceConstruct#interpret and
RecurrenceConstruct#variant_of? into the same method

Should be more efficient and reduces the amount of code
Reindented ZDate as suggested by rubocop
Used -= instead of longhand subtraction
Used + instead of += where the result was not needed
Used && instead of `and` where it was not needed
Reindented single-line if-statement
Removed double-hash comments
Reindented (the aptly named) ConstructFinder#big_if_on_current_word
Made NLP sort occurrences using Enumerable#sort_by! (on start date)
rather than manually specifying a sort block