hterm 1.56: sync changelog with recent commits.
hterm 1.56: sync changelog with recent commits.

* Fix mouse reporting.  Previously users had to click, then move the mouse
  before mouse reporting would start.
* Deal with surrogate pairs more properly.
* Add customizable keybindings.
* hterm_preference_manager.js: Group prefs into categories, declare input types
  rather than guess based on default value, improve layout.

Change-Id: I67af1239421c9bdd0e475ab0920e7ceae306ce43
Reviewed-on: https://chromium-review.googlesource.com/278052
Reviewed-by: Rob Ginda <4419ac4e35d191308e944202d542b192188656d1@chromium.org>
Tested-by: Rob Ginda <4419ac4e35d191308e944202d542b192188656d1@chromium.org>

hernad/libapps,hernad/libapps,hernad/libapps,hernad/libapps