Implement device IO as a shared library

Provide make targets and build configuration to create a shared object
for other systems/applications to use to control keyboard LEDs without
 the need for instantiating the g810-led process.

Provide make targets for installing library and development files into
environments, such as the current system or package builders.

Currently preserves precious behavior of building g810-led binary as
statically linked. Provides an alternative build target of "bin-linked"
which will create a dynamically linked variant.

Signed-off-by: Kevin Pearson <pearson.kevin.m@gmail.com>

.gitignore

@@ -1,3 +1,4 @@
 g810-led.*
 bin/*
+lib/*
 .