Feature request: allow specifying file extensions to ignore

[Joseph Garvin]

I have the misfortune of working with a build system where the compiled files are placed alongside the source files rather than a separate directory, and where C source files are preprocessed and the preprocessed output is saved in an intermediate file in the source directory. This means when I run global, because it indexes any text file it finds, that it's wasting time scanning the preprocessed output and not just the source file. Because global doesn't have a way to ignore specific file extensions, I don't have a way to prevent it from doing this. Additionally, sometimes generated source is kept in the source tree as a source of comparison against code produced by newer versions of a code generator, and I'd prefer that that code never get indexed, which could also be solved by being able to ignore extensions. Finally, global appears to look at files prefixed with ".#" which are my emacs backup files, which I definitely don't want scanned.

These could all potentially be resolved individually, but it'd probably be easiest to just let users specify extensions for global to ignore.