SWORD1: Fix speech endianness heuristic on big endian systems

This should fix bug #6720.
SYMBIAN: Updated settings and moved to config.mmh
SYMBIAN: Additional makefile updates.
I18N: Really fix speech endianness heuristic on big endian system

The previous commit was wrong because the endianness does not only
impact the data sample values but also the way the speech is uncompressed.
SCUMM: Fix bug #6724 by changing the assert into a warning