Clang and GCC: Large number of warnings at -Wall

[RichardTea]

Draco also cannot be built or used using Clang or GCC with -Wall -Werror

This makes it rather difficult (and noisy) to integrate into many modern projects, as it is often recommended to have -Wall -Werror enabled.

The warnings I have disabled to build 1.4.1 are: "-Wno-absolute-value" "-Wno-bool-compare" "-Wno-comment" "-Wno-maybe-uninitialized" "-Wno-sign-compare" "-Wno-unused-local-typedefs"

It also appears that the following warnings must be disabled via pragma in order to use the library for glTF: "-Wno-bool-compare" "-Wno-sign-compare"