Phillbush Xnotify Versions Save

• OpenBSD: revert breaking pledge call

• OpenBSD: Pledge tightening (#39)
• xnotify.1: Fix manual troff source (#38)

Just improve Makefile for better porting/packaging.

• add -w
• add BAR:
• add line trimming and line breaking
• add pledge call (OpenBSD)
• several bug fixes

• add support for specifying time for notification to be alive
• simplify invocation (replace "<... 3<>..." with "0<>...")
• handle SIGUSR1 and SIGUSR2
• minor code changes (rename variables, etc)