Implement new potential directive keyword test

Now we can use directive names as variables and targets type, for
example:

print = foo # variable
print{foo}: # target

1 files changed, 2 insertions, 0 deletions

diff --git a/tests/keyword/test.out b/tests/keyword/test.out
new file mode 100644
index 0000000..729af10
--- /dev/null
+++ b/tests/keyword/test.out
@@ -0,0 +1,2 @@
+a b c d e
+test