Pyreadstat

* read_file_in_chunks can read chunks with multiprocessing.

* Improved performance specially for big files.
* added a method to read files in parallel
* added license information to setup.py

* Updated default widths for DATE and DATETIME formats (from Readstat src). That makes the files readable both in SPSS and PSPP,
solves issue 69.
* added support for binary compressed sas7bdat files
* fixes writing XPT files v8 that can be read in SAS. Reading XPT v8 improved.
* fixes writing files with NaT values.
* fixes 72: variable display width with long strings.
* fixes 70: variable_measures not set when writing sav files
* updated Readstat to commit 02562413ded25e920b96bbbfc4d87ed062aacec8, version 1.1.4

* improved error messages when column names have spaces
* updated readstat to release 1.1.3: improved support for columns with
utf-8 characters.
* bumped version to first stable release as the library looks stable