Added path iteration and chained directories

All path iteration all goes through the lfs_dir_find function,
which manages the syntax of paths and updates the path pointer
to just the name stored in the dir entry.

Also added directory chaining, which allows more than one block
per directory. This is a simple linked list.

tests/test.py

@@ -10,9 +10,8 @@ def generate(test):
         template = file.read()
 
     lines = []
-
     for line in re.split('(?<=[;{}])\n', test.read()):
-        match = re.match('( *)(.*)=>(.*);', line, re.MULTILINE)
+        match = re.match('(?: *\n)*( *)(.*)=>(.*);', line, re.MULTILINE)
         if match:
             tab, test, expect = match.groups()
             lines.append(tab+'res = {test};'.format(test=test.strip()))
@@ -33,13 +32,17 @@ def execute():
     subprocess.check_call(["./lfs"])
 
 def main(test=None):
-    if test:
+    if test and not test.startswith('-'):
         with open(test) as file:
             generate(file)
     else:
         generate(sys.stdin)
 
     compile()
+
+    if test == '-s':
+        sys.exit(1)
+
     execute()
 
 if __name__ == "__main__":