Tcl_Concat is a utility procedure used by several of the Tcl
commands. Given a collection of strings, it concatenates them
together into a single string, with the original strings separated
by spaces. This procedure behaves differently than Tcl_Merge, in that the arguments
are simply concatenated: no effort is made to ensure proper list
structure. However, in most common usage the arguments will all be
proper lists themselves; if this is true, then the result will also
have proper list structure.
Tcl_Concat eliminates leading and trailing white space as
it copies strings from argv to the result. If an element of
argv consists of nothing but white space, then that string
is ignored entirely. This white-space removal was added to make the
output of the concat
The result string is dynamically allocated using Tcl_Alloc; the caller must eventually
release the space by calling Tcl_Free.