Feature: CMake now generates compile_commands.json

This commit adds suppotr for generating a 'compile commands' JSON
file. This provides fairly sufficient autocomplete support for most text
editors, such as (Neo)vim and VS Code. It specifies include paths, and
the compiler arguments used to compile each source file.

Signed-off-by: Dom Rodriguez <shymega@shymega.org.uk>

CMakeLists.txt

@@ -21,6 +21,7 @@ project (barrier C CXX)
 option (BARRIER_BUILD_GUI "Build the GUI" ON)
 option (BARRIER_BUILD_INSTALLER "Build the installer" ON)
 
+set (CMAKE_EXPORT_COMPILE_COMMANDS ON)
 set (CMAKE_CXX_STANDARD 14)
 set (CMAKE_CXX_EXTENSIONS OFF)
 set (CMAKE_CXX_STANDARD_REQUIRED ON)