Clean up the port

• Remove unnecessary variables such as USE_REINPLACE
• Define ETCDIR and use it throughout the port
• Use OPT_VARIABLE instead of if statements with PORT_OPTIONS:MOPT
• Sort variables and targets
• Sort pkg-plist and remove unnecessary @dir uses
• Define DOCS and EXAMPLES options for completeness
• Instal manuals under share/man

Approved by: portmgr blanket