Revert PR #22

[pnkfelix]

Revert "Add a hook so that we briefly highlight the matching < when > is typed."

This reverts commit 55e7483.

Undoing PR #22 since it broke emacs23 support.

[rust-highfive]

r? @nikomatsakis

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[pnkfelix]

Travis build failure is here: https://travis-ci.org/rust-lang/rust-mode/jobs/49740311

[nikomatsakis]

@MicahChalmer any tips on how we can fix emacs23 instead?

[nikomatsakis]

@MicahChalmer also...why do we care about emacs23? I guess some non-trivial number of people still use it?

[nikomatsakis]

@MicahChalmer final ping :) any tips on how to get a working install of emacs23 that can run unit tests? I get errors about ert not being installed.

[pnkfelix]

(lets just disable emacs23 tests for the short term)

[MicahChalmer]

Yipes...unfortunately I was not available during the day to get to this that quickly!

ERT was a standalone package through emacs 23, but was then made part of emacs for emacs 24. In the travis config, I have it download it from https://raw.githubusercontent.com/ohler/ert/c619b56c5bc6a866e33787489545b87d79973205/lisp/emacs-lisp/ert.el (that URL is still present in the .travis.yml here, but the use of it in the build has been disabled by #26. Grab it and put it in a place where emacs will know where to find it (the site-lisp directory where it's installed, for instance) and the tests will run.