Check unnecessary visibility for struct variants
remove rust and rusti from driver.rs
std::fmt: fix markdown peculiarity, unicodify some arrows, ` some trait names.
auto merge of #9949 : Heather/rust/driver-rs-cleanup-pullrequest, r=thestinger
auto merge of #9952 : huonw/rust/fmt-doc, r=alexcrichton

Cf. the concern raised in https://github.com/mozilla/rust/pull/9938#issuecomment-26648696.
auto merge of #9956 : sfackler/rust/more-more-visibility, r=alexcrichton
Allow fail messages to be caught, introduce Any trait
Some code cleanup, sorting of import blocks
Removed std::unstable::UnsafeArc's use of Either