osx makefile backporting of commit be34510a9a17b3be83e817d6e58c9023a48e75bc
Fixed the ubuntu building doc

Tested on pristine Ubuntu 12.04 LTS and 13.10
disable safemode & add checkpoint
bugfix: weak checking for existing users (the transaction may exist in index only
but the chain it belongs was invalidated) caused fork between users who erased their
block database from yesterday and those who didn't. improve the checking (test
if tx is actually in main chain). add another checkpoint. enforce.
Merge pull request #49 from toyg/osx_makefile_backport

osx makefile backport of be34510
Merge pull request #51 from lra/better_ubuntu_doc

Fixed the ubuntu building doc
generalize checking if tx is in mainchain for GetTransaction
move spamuser key validation from CheckTransation to ConnectBlock.
reason: this is not context-independent validation.
trying to fix infinite recursion in SetBestChain
update version
some nodes are still on the wrong chain (block 18973 with an invalid spamuser). checkpoint the
correct branch to force them to go to the right chain.
fix "CreateNewBlock() : ConnectBlock failed" due to "duplicate username".
improve transaction collect in CreateNewBlock
partialy revert changeset 77d1a4fb. fixed one case (that -reindex would fix anyway) but broke another one.
rpcallowip is important
Called out debug.log
Join multiple dhtget responses. fix #14
Merge pull request #60 from vdm/patch-1

Called out debug.log
validate post to promote. fix #34
missing function. thanks jpfox
Fixed small typo