Ignore some more generated files.

.gitignore

@@ -1,6 +1,8 @@
 build
 Build
 Build.bat
+*/external/Catch
+Makefile
 MYMETA.json
 MYMETA.yml
 _build
@@ -26,3 +28,9 @@ CMakeCache.txt
 src/test/test_options.hpp
 src/slic3r
 build/*
+
+slic3r
+gui_test
+slic3r_test
+compile_commands.json
+tags