Release v3.1

• Clean build directory and temp directory
• Expanded -G to fetch old AUR package source (-G foobar~ or -G foobar==2.0-1)
• Added new exit codes
• Converted apacman.8 and apacman.conf.5 manpages to HTML
• Fixed #75
• Fixed #72
• Fixed #73
• Merged pull request #76
• Merged pull request #74
• Miscellaneous fixes and cleanup