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, 3 insertions, 0 deletions

diff --git a/tests/keyword/test.sh b/tests/keyword/test.sh
new file mode 100755
index 0000000..b898b3c
--- /dev/null
+++ b/tests/keyword/test.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+
+valgrind -q b -q | diff -u test.out -