npsf v0.3.0 (Release date: 2018-01-16)

* Fixed various bugs
* Own LP solver instead of glpk
* added nobs() method for objects of class 'npsf'
* added summary() method for objects of class 'npsf'
* added print() method for objects of class 'npsf'
* added vcov() method for objects of class 'npsf' 
  (relevant for function 'sf')
* added coef() method for objects of class 'npsf'
  (relevant for function 'sf')

npsf v0.2.0 (Release date: 2017-01-19)

* Fixed bugs with data preparation
* Fixed initial values for truncated regression (truncreg) estimation

npsf v0.1.9 (Release date: 2016-09-02)

* Fixed some bugs with data preparation
* Added truncated regression (truncreg) estimation with 
  lower and upper bounds (which can be specified simultaneously)

npsf v0.1.8 (Release date: 2016-07-05)

* Added nobs(), coef(), and vcov() for all relevant objects
* Added summary() and print() for all relevant objects
* Fixed some bugs with names in sf
* Fixed documentation

npsf v0.1.6 (Release date: 2015-09-20)

* Initial release of the npsf package on CRAN