FEAT: added internal remove-char function for string datatype. FIX: minor code improvement in insert-char function.
FEAT: added internal remove-char function for string datatype.
FIX: minor code improvement in insert-char function.

NikolayShubenkovProgSchool/red,rheber/red,vehar/red,vehar/red,red-eco/red,NikolayShubenkovProgSchool/red,rheber/red,red-eco/red