Due to ``#include "DallasFuncs.cpp"``, DF is recompiled 52 times.
Rework it to build just once. The compile time goes down for me
from 1m45.3s to 1m38.8s on my 1135G7 CPU running make -j8.
The vast majority of this is fixing up `char *` that should be `const char *`
but a handful of other fixes, like potential buffer overflows that GCC
noticed, etc, were applied as well.
This removes `-Wno-write-strings` from CMakeLists.txt, as it is no longer
necessary, as there is no longer a flood of compiler warning spam when
building.
This does not fix all compiler warnings; there are still a handful, and they
are legitimate, but they can be dealt with in a future commit.
Most of the warnings were caused by uninitialized values. Some were in plug-ins that didn't have a break in a switch, causing the memory to be deleted twice.
