Merge with crew

Fix hg view if author's name contains unmatched quotes. (issue248) This was caused by the often seen Tcl list vs. string programming error.

notify changeset diff should be against current node instead of tip

fix a typo in an error message

Catch urllib's HTTPException and give a meaningful error message to the user. Usually urllib only throws HTTPError exceptions, which already are a subclass of IOError.

add --config global option. allows to set hgrc option on command line. syntax: --config section.name=value also add new test-globalopts to test all global options in one place.

allow to send email using sendmail. default is still smtp. update hgrc doc with sendmail info.

merge with crew.

add test for revlog.parseindex

Fix revlog.parseindex parseindex could fail if read returns too little data in the right moment (e.g. when there's still leftover data from the previous iteration and read returns less than "s" bytes).