rename files from rb to rbt

diff --git a/source/rb/rb.c b/source/rbt/rbt.c
similarity index 100%
rename from source/rb/rb.c
rename to source/rbt/rbt.c

diff --git a/source/rb/rb.h b/source/rbt/rbt.h
similarity index 100%
rename from source/rb/rb.h
rename to source/rbt/rbt.h

diff --git a/tests/test_rb.c b/tests/test_rbt.c
similarity index 100%
rename from tests/test_rb.c
rename to tests/test_rbt.c