Changed (pseudo) code line referencing to line numbers.
Fixed tests for code.code setCurrentLine
Added tests for tags
Merge pull request #157 from X455u/critical

Changed code referencing to line numbers
Translated the animation control button titles; had to change the order of files in the Makefile
Changed the signature of the jsav.exercise() function by moving compare to options
Updated the example exercise to match the new jsav.exercise() function
Set the same top/bottom margin for all jsav structures
Fixed a bug in matrix visibility
Added layered graph layout using dagre (https://github.com/cpettitt/dagre)
Added .clear() function to graphical primitives
Improved the edge layout to better work with rounded rectangle nodes
Fixed layered graph layout node positioning
Fixed a bug in pseudocode which prevented using centered, initially hidden codes
Removed margins from pointer label
Minor improvement to pointers example