[libcvd-members] Critical fix!

[Edward Rosten]

There is an off by one bug in building the static lookup tables for byte 
to float conversion in scalar convert.

This was trashing the static `instance' variables in GVars3, causing a 
segfault. But only for gvars of std::strings. And only if I put the 
arguments to the linker in the `wrong' order. Not to mention having a 
static list<Image<float> > *before* main in the code.

-Ed