linespacing_fix.sty

\NeedsTeXFormat{LaTeX2e}[1994/06/01]
\ProvidesPackage{linespacing_fix}[2015/06/06 linespacing_fix Package]

% fix extra space introduced by setspace
% http://tex.stackexchange.com/questions/138752/unnecessary-space-after-endspacing
\RequirePackage{setspace}
%% insert the following material in preamble
\RequirePackage{calc}
\newlength\modparskip
\newlength\modbaselineskip
  \def\baselinestretch{1} % this parameter will be redefined at start of 'spacing' environment
  \setlength\modparskip{\parskip/\real{\baselinestretch}}%
  \setlength\modbaselineskip{\baselineskip/\real{\baselinestretch}}%
\makeatletter
\renewenvironment{spacing}[1]{\par%
   \def\baselinestretch{#1}%
   \ifx\@currsize\normalsize\@normalsize\else\@currsize\fi%
}%
{\par%
   \vskip \modparskip%      % originally: \vskip \parskip
   \vskip \modbaselineskip% % originally: \vskip \baselineskip
}
\makeatother
%% end of material to be inserted in preamble