Standard Tx Modifications

* Remove contentious sentence about mining non-standard txes possibly
  creating orphaned blocks and loss of block reward.  Suggested by
  @luke-jr (thanks!)

* Remove unnecessary value judgement ("unfortunately") against
  non-standard redeemScripts. Mention that they can be used deliberately
  by someone who wants to easily receive payment to a non-standard
  output script. Suggested by @luke-jr (thanks!)