This reverts commit 119c200e00.

This replaces uses of:

	memcpy(dst, src, strlen(src))

with:

	strcpy(dst, src)

This fixes issues with reading past the end of the copied buffer
(e.g. when processing word-based replacements for emoji characters)
by ensuring that the destination buffer is null terminated.

Reported by Michael Curran <[email protected]>

Clang static analysis reports this as 'Assigned value is garbage
or undefined'.

Clang static analysis reports these as 'Result of operation is
garbage or undefined' errors.

Clang static analysis reports an 'Assigned value is garbage or
undefined' for this. If no points were read from the file, the
`n_points` variable is 0 and `env_x[n_points-1]` performs an
out-of-bounds access.

Clang static analysis reports an 'Assigned value is garbage or
undefined' error. This happens if the default_tune data has not
been copied in the kTUNE case.

Extending this further, it does not make sense to save the tune
data if the tune was not found, or if the tune already exists.

This was identified by the clang static analyser. The letter
variable is set in the various match_type switch cases, so
does not need to be initialised in the start of the while loop.

This was identified by the clang static analyser.

Clang static analysis reports a 'Dereference of null pointer'
error when accessing wtab->flags. This is properly guarded
against when setting the wflags variable, so use that variable
instead.

Clang static analysis reports this as several 'Result of operation
is garbage or undefined' errors, when `ending` has not been set
due to no matching endings.