Re-organize directory structure (#4971)

See discussion in #2491

Co-authored-by: Ivan Levkivskyi <ilevkivskyi@dropbox.com>

stdlib/@python2/strop.pyi

@@ -0,0 +1,27 @@
+from typing import List, Sequence
+
+lowercase: str
+uppercase: str
+whitespace: str
+
+def atof(a: str) -> float: ...
+def atoi(a: str, base: int = ...) -> int: ...
+def atol(a: str, base: int = ...) -> long: ...
+def capitalize(s: str) -> str: ...
+def count(s: str, sub: str, start: int = ..., end: int = ...) -> int: ...
+def expandtabs(string: str, tabsize: int = ...) -> str: ...
+def find(s: str, sub: str, start: int = ..., end: int = ...) -> int: ...
+def join(list: Sequence[str], sep: str = ...) -> str: ...
+def joinfields(list: Sequence[str], sep: str = ...) -> str: ...
+def lower(s: str) -> str: ...
+def lstrip(s: str) -> str: ...
+def maketrans(frm: str, to: str) -> str: ...
+def replace(s: str, old: str, new: str, maxsplit: int = ...) -> str: ...
+def rfind(s: str, sub: str, start: int = ..., end: int = ...) -> int: ...
+def rstrip(s: str) -> str: ...
+def split(s: str, sep: str, maxsplit: int = ...) -> List[str]: ...
+def splitfields(s: str, sep: str, maxsplit: int = ...) -> List[str]: ...
+def strip(s: str) -> str: ...
+def swapcase(s: str) -> str: ...
+def translate(s: str, table: str, deletechars: str = ...) -> str: ...
+def upper(s: str) -> str: ...