Fix unique method for duration arrays to return a duration array as an output.

• causing regression in statistics package gnu-octave/statistics#408

Update overloaded disp and display methods for cell arrays to avoid printing empty char cells for empty cell arrays.

The calendarDuration class has been fully implemented including its documentation and testing suite.

• 52 public methods (including the constructor)
• 5 hidden methods (disp, display, end, subsref, subsasgn)
• 4 private methods (internal use only)
• 626 unit tests (covering all public and hidden methods)

Fix __disp__ private function to properly display arrays with more than 3 dimensions.
Update __unique__ private function to support specifying setOrder and occurrence together.

Fix csv2table to correctly load CSV files with blank values. (issue #29)
Revert support for assignment syntax (e.g. Name = Value) of optional properties in array2table and cell2table functions.

Add new parsePairedArguments function for parsing optional Name-Value properties.
Add support for assignment syntax (e.g. Name = Value) of optional properties in array2table and cell2table functions.
Allow table dimension indexing to return table contents as a cell array when table2array cannot concatenate all variables.
Fix minus and plus methods for calendarDuration and duration arrays.
Fix csv2table to properly load standard CSV files.
Fix split method for calendarDuration arrays.
Add times, mtimes, eq, and ne methods calendarDuration arrays.
Improve documentation and BIST coverage for the calendarDuration classdef.

Update tz.cpp to use tzdata distributed with the package in order to avoid the Windows dependency on 7-zip which is hardcoded in the date.h library. See issue #25 for more information.

Add end method to table class. (issue #10)
Add new isnat function to emit an error when input is not a datetime array.

Fix bugs in unique and table2cell methods of the table class.
Fix error in isvector method of table class. (issue #23)
Add more BISTs for the table class.

Fix overloading disp and display methods for cell arrays to correctly print the dimensions of empty cell arrays or the dimensions of nested empty arrays in cell elements.
Implement ismember method for datetime arrays.
Fix ismember method for categorical arrays to handle <undefined> elements.
Document ismember method for duration and string arrays.

Update license metadata for the package's logo in/doc/datatypes.png. (issue #22)
Include a LICENSE.txt for clarifying license terms of the package. (issue #22)

Update ismissing method in table class to handle mixed cell array as indicator argument.
Fix ismissing methods in all array objects.
Update calendarDuration functions to accept NaN values as missing values.
Fix cat method in categorical class to support concatenation with empty array.
Fix comparison operators in string arrays.
Fix input parser of mixed cell arrays in string constructor.
Change Makefile to allow cross compilation with mxe-octave. (issue #20)