Gcc 4.9 LTO fix

The new lto format requires use of the gcc-provided gcc-ar and
gcc-ranlib binaries.
Link to pthreads on non-apple unix
Fix to disable LTO for Clang

The previous code was assuming Apple == Clang.  This change should both
enable LTO when using gcc on Apple and fix Clang when using it on other
platforms.
needed to remove REQUIRED from find_package(Threads)
Added comments to wallet functions
proper tx_pool handling from CryptoZoidberg / BBR
working on dividing functions in prep for tx splitting
final changes to get transaction splitting building.  needs testing.
up tx splits limit 5 -> 30
added back successful tx message.  oops.
Added confirmation prompt if transactions are to be split
Transaction splitting *seems* to be working!!!
removed some debugging code (really stupid printf-style debuggng..
missed removing a debug print
removed erroneous printing of newlines
Merge branch 'master' of https://github.com/fluffypony/bitmonero