Clean-up usage of root directory in docs generation

Instead, make use of the current working directory.
This should ease most of it and remove noise, since
now root is just the current directory.

setup.py

@@ -12,9 +12,9 @@ Extra supported commands are:
 
 import itertools
 import json
+import os
 import re
 import shutil
-from os import chdir
 from pathlib import Path
 from subprocess import run
 from sys import argv
@@ -26,16 +26,19 @@ class TempWorkDir:
     """Switches the working directory to be the one on which this file lives,
        while within the 'with' block.
     """
-    def __init__(self):
+    def __init__(self, new=None):
         self.original = None
+        self.new = new or str(Path(__file__).parent.resolve())
 
     def __enter__(self):
-        self.original = Path('.').resolve()
-        chdir(str(Path(__file__).parent.resolve()))
+        # os.chdir does not work with Path in Python 3.5.x
+        self.original = str(Path('.').resolve())
+        os.makedirs(self.new, exist_ok=True)
+        os.chdir(self.new)
         return self
 
     def __exit__(self, *args):
-        chdir(str(self.original))
+        os.chdir(self.original)
 
 
 GENERATOR_DIR = Path('telethon_generator')
@@ -108,7 +111,9 @@ def generate(which, action='gen'):
             if DOCS_OUT.is_dir():
                 shutil.rmtree(str(DOCS_OUT))
         else:
-            generate_docs(tlobjects, methods, layer, DOCS_IN_RES, DOCS_OUT)
+            in_path = DOCS_IN_RES.resolve()
+            with TempWorkDir(DOCS_OUT):
+                generate_docs(tlobjects, methods, layer, in_path)
 
     if 'json' in which:
         which.remove('json')
@@ -223,5 +228,5 @@ def main():
 
 
 if __name__ == '__main__':
-    with TempWorkDir():  # Could just use a try/finally but this is + reusable
+    with TempWorkDir():
         main()