Stop ignoring gcoder_line cruft

The in-place build of the 'gcoder_line' extension is no longer
recommended. A command such as `python setup.py build_ext --inplace` is
deprecated. Therefore its outputs should no longer be ignored and should
be considered cruft that needs to be removed.

.gitignore

@@ -10,9 +10,6 @@ prontserve-env
 pronterface.spec
 pronsole.spec
 plater.spec
-printrun/gcoder_line.c
-printrun/gcoder_line*.so
-printrun/gcoder_line*.pyd
 .project
 .pydevproject
 /build/