Tweakable orphaned sections - revive old PR (#231)

* introduce different first and lastname styles.

* fix orphaned section headers (needs testing). Closes #10.

* introduce \cvsectionstretchability and \cvsubsectionstretchability

* set default stretchability to 0.9\baselineskip

* add fix orphaned section notice to changelog

---------

Co-authored-by: David <forenkram@gmx.de>

moderncvbodyv.sty

@@ -72,8 +72,18 @@
   % regular lengths
   \setlength{\parskip}{0\p@}}
 
+% leave the stretchability zero by default
+% \setlength{\cvsectionstretchability}{0.0pt}
+% \setlength{\cvsubsectionstretchability}{0.0pt}
+% must be between -100 and 9999. The higher the less likely a page break will occur.
+% This is where the page break should occur, so this number should not bee too high
+% \RenewDocumentCommand\withinstretchpenalty{}{0}
+% must be between -100 and 9999. The higher the less likely a page break will occur.
+% \RenewDocumentCommand\poststretchpenalty{}{9999}
+
 \@initializeif{\if@aftersection}\@aftersectionfalse%
 \RenewDocumentCommand{\section}{sm}{%
+  \@cvneedspace{\cvsectionstretchability}% avoid orphaned sections
   \addvspace{2.5ex}%
   \phantomsection{}% reset the anchor for hyperrefs
   \addcontentsline{toc}{section}{#2}%
@@ -83,6 +93,7 @@
 
 %\@initializeif{\if@aftersubsection}\@aftersubsectionfalse%
 \RenewDocumentCommand{\subsection}{sm}{%
+  \@cvneedspace{\cvsubsectionstretchability}% avoid orphaned sections
   %\addvspace{1ex}%
   \vspace*{-\arrayrulewidth}% HACK; I don't understand where the space is coming from, nor what it's exact value is :(
   \if@aftersection%