Watch files outside the src directory for changes when they are included from a file we are watching

[paulpr0]

Currently, you can include files from anywhere, so inside file myfile.txt

--include /etc/motd

works fine, but when using the -w flag to watch for changes, any changes to /etc/motd will not cause myfile.txt to be regenerated.

Adding the path of the file to the watcher when we detect that it's outside of the src root would allow for this