This commit adds the code necessary to generate a new
en/developre-glossary page with entry pages in the en/glossary/
directory, e.g. en/glossary/51-percent-attack.

The glossary page and the individual term pages feature a JavaScript
search engine (no CGI) for just glossary terms.  This search box has
also been added to the following pages:

    * Developer Documentation (the index page)
    * Developer Guide
    * Developer Reference
    * Developer Examples

The search box requires the following MIT-licensed libraries:

    * JQuery
    * JQuery UI
    * JQuery UI CSS stylesheet

These allow our JS code to be almost trivially simple in js/devsearch.js

This commit adds only code.  Actual glossary entry data will be added in
a subsequent commit.

This adds the data used to populate the glossary and search terms.

Closes bitcoin-dot-org#593

Add link to the glossary from each definition
Fix missing BIP37 link
Fix searchbox width on mobiles
Apply more consistent margin and padding for the searchbox
Use H3 titles in the glossary_entry layout for better readability
Always use HTML classes for CSS stylesheets
Fix one typo in glossary.rb