Set lexer for VHDL language.

Conflicts:

	test/test_blob.rb

test/fixtures/foo.vhd

@@ -0,0 +1,14 @@
+-- VHDL example file
+
+library ieee;
+use ieee.std_logic_1164.all;
+
+entity inverter is
+	port(a : in std_logic;
+	     b : out std_logic);
+end entity;
+
+architecture rtl of inverter is
+begin
+	b <= not a;
+end architecture;