[ticket/10970] Paths of the form {FOO}/a/{BAR}/b parsed correctly

A new method to handle this type of path was added and
compile_tag_include, compile_tag_include_php and
compile_tag_include_js were modified to use it appropriately.

Tests were added for these three macros also.

PHPBB3-10970

tests/template/template_test.php

@@ -183,6 +183,13 @@ class phpbb_template_template_test extends phpbb_template_template_test_case
 				array(),
 				'value',
 			),
+			array(
+				'include_variables.html',
+				array('SUBDIR' => 'subdir', 'VARIABLE' => 'value'),
+				array(),
+				array(),
+				'value',
+			),
 			array(
 				'loop_vars.html',
 				array(),