Intermediate commit for #714 Fixed some detected problems.
Intermediate commit for #714 Tried to unify the internal string representation.
Intermediate commit for #714
Added new changes to #714 The StringFuncArgs structure was updated to use only copy efficient views
Created branch for ticket #714
Fixed issue #715 "Avoid strings to last over the a line in input history"
Fixed issue #716 "Shorten string variables in GUI"
Implemented ticket #713 "Control flow headers should accept interrupts"
Implemented ticket #712 "Eigenvalues and eigenvectors from NANs"