remotenames: add functionality to hoist remotebookmarks This patch adds the functionality to hoist remotebookmarks to the top level namespace. The peer of which bookmarks should be hoisted can be set using `remotenames.hoistedpeer` config option. Only bookmarks can be hoisted. If a hoisted name and local bookmark exists of the same name, the local bookmark takes precedence. While I was here, I documented the default values of two other remotenames config options. Differential Revision: https://phab.mercurial-scm.org/D2807

  $ hg init
  $ touch a

  $ unset HGUSER
  $ echo "[ui]" >> .hg/hgrc
  $ echo "username= foo" >> .hg/hgrc
  $ echo "          bar1" >> .hg/hgrc

  $ hg ci -Am m
  adding a
  abort: username 'foo\nbar1' contains a newline
  
  [255]
  $ rm .hg/hgrc

  $ HGUSER=`(echo foo; echo bar2)` hg ci -Am m
  adding a
  abort: username 'foo\nbar2' contains a newline
  
  [255]
  $ hg ci -Am m -u "`(echo foo; echo bar3)`"
  adding a
  transaction abort!
  rollback completed
  abort: username 'foo\nbar3' contains a newline!
  [255]