Remove deprecated clean_filename and clean_timestamp utilities (#1820)

This PR removes the deprecated `clean_filename` and `clean_timestamp`
utilities.

Author: mdickinson

traits/util/clean_strings.py

@@ -13,110 +13,7 @@
 """
 
 # Standard library imports.
-import copy
-import datetime
 import keyword
-import re
-import unicodedata
-import warnings
-
-
-def clean_filename(name, replace_empty=""):
-    """
-    Make a user-supplied string safe for filename use.
-
-    Returns an ASCII-encodable string based on the input string that's safe for
-    use as a component of a filename or URL. The returned value is a string
-    containing only lowercase ASCII letters, digits, and the characters '-' and
-    '_'.
-
-    This does not give a faithful representation of the original string:
-    different input strings can result in the same output string.
-
-    .. deprecated:: 6.3.0
-        This function will be removed in a future version of Traits.
-
-    Parameters
-    ----------
-    name : str
-        The string to be made safe.
-    replace_empty : str, optional
-        The return value to be used in the event that the sanitised
-        string ends up being empty. No validation is done on this
-        input - it's up to the user to ensure that the default is
-        itself safe. The default is to return the empty string.
-
-    Returns
-    -------
-    safe_string : str
-        A filename-safe version of string.
-
-    """
-    warnings.warn(
-        "clean_filename is deprecated and will eventually be removed",
-        DeprecationWarning,
-        stacklevel=2,
-    )
-
-    # Code is based on Django's slugify utility.
-    # https://docs.djangoproject.com/en/1.9/_modules/django/utils/text/#slugify
-    name = (
-        unicodedata.normalize('NFKD', name)
-        .encode('ascii', 'ignore')
-        .decode('ascii')
-    )
-    name = re.sub(r'[^\w\s-]', '', name).strip().lower()
-    safe_name = re.sub(r'[-\s]+', '-', name)
-    if safe_name == "":
-        return replace_empty
-    return safe_name
-
-
-def clean_timestamp(dt=None, microseconds=False):
-    """
-    Return a timestamp that has been cleansed of characters that might
-    cause problems in filenames, namely colons.  If no datetime object
-    is provided, then uses the current time.
-
-    The timestamp is in ISO-8601 format with the following exceptions:
-
-    * Colons ':' are replaced by underscores '_'.
-    * Microseconds are not displayed if the 'microseconds' parameter is
-        False.
-
-    .. deprecated:: 6.3.0
-        This function will be removed in a future version of Traits.
-
-    Parameters
-    ----------
-    dt : None or datetime.datetime
-        If None, then the current time is used.
-    microseconds : bool
-        Display microseconds or not.
-
-    Returns
-    -------
-    A string timestamp.
-    """
-    warnings.warn(
-        "clean_timestamp is deprecated and will eventually be removed",
-        DeprecationWarning,
-        stacklevel=2,
-    )
-
-    if dt is None:
-        dt = datetime.datetime.now()
-    else:
-        # Operate on a copy.
-        dt = copy.copy(dt)
-
-    if not microseconds:
-        # The microseconds are largely uninformative but annoying.
-        dt = dt.replace(microsecond=0)
-
-    stamp = dt.isoformat().replace(":", "_")
-
-    return stamp
 
 
 def python_name(name):