Add pitfalls section, improve difficulties section

VL1/VL1_document_structure.tex

@@ -112,9 +112,14 @@
 
 \slide{./content/VL1_common_misconceptions.tex}
 
+\subsection{Pitfalls}
+
+\slide{./content/VL1_pitfalls.tex}
+
 \subsection{Difficulties}
 
-\slide{./content/VL1_difficulties.tex}
+\slide{./content/VL1_difficulties1.tex}
+\slide{./content/VL1_difficulties2.tex}[ (cnt.)]
 
 \section{Toolchain}
 

VL1/content/VL1_difficulties1.tex

@@ -6,6 +6,4 @@ Haskell is very powerful and can be used for pretty much anything. However, ther
 \item no premium-like IDE with every possible feature (yet)
 \item dynamic linking is sort of WIP yet, lots of ABI breakage
 \item because most of the world thinks in imperative style languages, it's often difficult to find pseudo-code for functional style languages, so you end up reverse-engineering algorithms
-\item some problems that are trivial in imperative languages, can be very difficult to solve in idiomatic haskell and vice versa
-\item practical cryptography is possible, but a difficult topic in haskell, see \url{https://mail.haskell.org/pipermail/haskell-cafe/2015-February/118059.html}
 \end{itemizep}

VL1/content/VL1_difficulties2.tex

@@ -0,0 +1,5 @@
+\begin{itemizep}
+\item some problems that are trivial in imperative languages, can be very difficult to solve in idiomatic haskell and vice versa
+\item practical cryptography is possible, but a difficult topic in haskell, see \url{https://mail.haskell.org/pipermail/haskell-cafe/2015-February/118059.html}
+\item although haskell is \emph{lazy}, there are a few things that can break laziness, see \url{https://wiki.haskell.org/Maintaining_laziness}
+\end{itemizep}

VL1/content/VL1_pitfalls.tex

@@ -0,0 +1,3 @@
+\begin{itemizep}
+\item none...
+\end{itemizep}