Log Message:
Update py-Xlib to 0.28

Version 0.28
============

Extensions
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- DPMS: Display Power Management Signaling (by @thiagokokada)

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Version 0.27
============

Bug Fixes
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- fix TypeError in socket.error exception handling for Python 3.x (by @t-wissmann)

Extensions
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- NV-CONTROL: set offset for all perf levels (by @Sporif)

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Version 0.26
============

Bug Fixes
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- support legacy X servers like RealVNC's one (by @Gerardwx)

Extensions
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- enrich XFixes extension with XFixesSelectionNotify events (by @acrisci)
- add example xfixes-selection-notify.py (by @acrisci)
- fix two issues in NV-CONTROL extension (by @leinardi)
- add method get_clock_info into NV-CONTROL extension (by @leinardi)
- add default client version into Composite extension (by @jakogut)
- add Damage extension with the example (by @mgarg1 and @jakogut)