Fixed an issue when configuration file options partly ignored when `--project-conf` // Resolve #3034 (#3055)

* Fixed an issue when configuration file options partly ignored when using custom ``--project-conf`` // Resolve #3034

* Py2 compatible makedirs

* Fix circle dependency

* Fix broken import in test examples

* Fix history

* Remove YAPF markers

* PyLint fix

* Fix invalid project conf path

* Move PIO Core to the root on Windows, issue with long CPPPATHs

* Respect global PLATFORMIO_BUILD_CACHE_DIR env var

* Fix Appveyor paths

* Minor changes

platformio/app.py

@@ -17,7 +17,7 @@ import hashlib
 import os
 import uuid
 from os import environ, getenv, listdir, remove
-from os.path import abspath, dirname, expanduser, isdir, isfile, join
+from os.path import abspath, dirname, isdir, isfile, join
 from time import time
 
 import requests
@@ -25,21 +25,11 @@ import requests
 from platformio import exception, fs, lockfile
 from platformio.compat import WINDOWS, dump_json_to_unicode, hashlib_encode_data
 from platformio.proc import is_ci
-from platformio.project.helpers import get_project_cache_dir, get_project_core_dir
-
-
-def get_default_projects_dir():
-    docs_dir = join(expanduser("~"), "Documents")
-    try:
-        assert WINDOWS
-        import ctypes.wintypes
-
-        buf = ctypes.create_unicode_buffer(ctypes.wintypes.MAX_PATH)
-        ctypes.windll.shell32.SHGetFolderPathW(None, 5, None, 0, buf)
-        docs_dir = buf.value
-    except:  # pylint: disable=bare-except
-        pass
-    return join(docs_dir, "PlatformIO", "Projects")
+from platformio.project.helpers import (
+    get_default_projects_dir,
+    get_project_cache_dir,
+    get_project_core_dir,
+)
 
 
 def projects_dir_validate(projects_dir):
@@ -88,7 +78,12 @@ DEFAULT_SETTINGS = {
     },
 }
 
-SESSION_VARS = {"command_ctx": None, "force_option": False, "caller_id": None}
+SESSION_VARS = {
+    "command_ctx": None,
+    "force_option": False,
+    "caller_id": None,
+    "custom_project_conf": None,
+}
 
 
 class State(object):
@@ -415,6 +410,6 @@ def get_cid():
         uid = uuid.getnode()
     cid = uuid.UUID(bytes=hashlib.md5(hashlib_encode_data(uid)).digest())
     cid = str(cid)
-    if WINDOWS or os.getuid() > 0:  # yapf: disable pylint: disable=no-member
+    if WINDOWS or os.getuid() > 0:  # pylint: disable=no-member
         set_state_item("cid", cid)
     return cid