#5 bpc_error_allocate const char *

[Christoph Pfisterer]

This patch changes bpc_error_allocate to use (const
char *) arguments instead of (char *). This is very
useful for functions that need to call
bpc_error_allocate with strings that they have received
as a (const char *) themselves. It would be nice to see
similar changes all over beepcore-c, but this is likely
a big task.

The patch also corrects the buffer length counting. It
can be off by one when quoting an ampersand in the
diagnostic.

[Christoph Pfisterer]

Patch against CVS 2002-09-20