- Support for python 2.6 dropped. New minimum version is 2.7
- Add support for tmux 2.4, pypy and pypy3
- Overhaul error handling when setting and showing options
- Added `handle_option_error` for handling option errors
- Added {exc}`libtmux.exc.OptionError` base exception
- Added {exc}`libtmux.exc.InvalidOption` and `libtmux.exc.AmbiguousOption`
- {exc}`libtmux.exc.UnknownOption` now extends {exc}`libtmux.exc.OptionError`
- Overhaul version checking
- `has_version` has been renamed to `get_version`
- `get_version` will return tmux built from git master as the latest version supported by the libtmux version with `-master` at the end, e.g. `2.4-master`
- `get_version` will return tmux on openbsd base system as the latest version supported by the libtmux version with `-openbsd` at the end, e.g. `2.4-openbsd`
- `has_required_tmux_version` has been renamed to `has_minimum_version`
- added `has_gt_version`, `has_gte_version`, `has_lt_version`, `has_lte_version`,
- Fixed up documentation in some session methods
- Added pydoc exception info to option methods in window and sessions.
- Added `TMUX_MIN_VERSION` and `TMUX_MAX_VERSION`