Imio.pyutils

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- Added patterns parameter in `system.read_dir_filter`.
[sgeulette]
- Returned original filename in `system.hashed_filename` if string to hash is empty.
[sgeulette]

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- Require `six>=1.16.0`.
[sgeulette]
- Added `system.hashed_filename` to get a new filename differentiated by a hashed string.
[sgeulette]

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- Handled set in `load_var`.
[sgeulette]
- Added `load_pickle` and `dump_pickle`
[sgeulette]
- Improved `bs.is_empty`
[sgeulette]

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- Made py2 and py3 compliant
[sgeulette]
- Improved `utils_safe_encode`
[sgeulette]
- Added `bs.is_empty` function.
[sgeulette]
- Added `bs.remove_some_childrens` function.
[sgeulette]
- Added `bs.replace_strings_by_pattern` function
[sgeulette]
- Added `exclude_patterns` parameter in `system.read_recursive_dir`
[sgeulette]

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- Added `utils.listify` that will make sure a given value
is always returned as list-like iterable.
[gbastien]
- Improved `system.get_git_tag` with new parameter to get last tag from all branches
[sgeulette]
- Added `utils.radix_like_starting_1` to get list of positional numbers following a given base but starting with 1
[sgeulette]
- Added `utils.letters_sequence` to get a letters string corresponding to nth position
[sgeulette]

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- Added `system.read_recursive_dir` to get files recursively (with relative or full name).
[sgeulette]