Allocates a string on the heap.
function StrNew(Str: PChar): PChar;;
StrNew allocates a copy of Str on the heap.
If Str is nil or points to an empty string, StrNew returns nil and does not allocate any heap space.
Otherwise, StrNew makes a duplicate of Str, obtaining space with a call to thestandard procedure, and returns a pointer to the duplicated string.
The allocated space is StrLen(Str) + 1 bytes long.