Update to 1.8.99.7

• Lots of important fixes in the solver
• Fix pkg upgrade -f
• Reduce namecache contention a bit
• Prefix all temporary files with a . so they are hidden
• Explicitly tell the users which conflicts were found
• Do not fork pkg when being ptraced (only on FreeBSD)
• Implement repo pinning so once installed a package will keep coming from a given repo
• Fix repository priority handling on directly requested packages

Big thanks az@ and vsevolod@ for the thank less help provided