Travis CI: Syntax check XML files

Fixes #208
Don't use the width attribute on th elements

See #204
Remove an unnecessary action attribute from a form

We’re submitting the form to the same page, so it isn’t necessary.
Also, the PHP generated value wasn’t being `echo`ed anyway.

Fixes #204
Merge branch 'issue-204'
Late escape admin messages

See #72
Refactor module list table row display

For better late escaping and code clarity.

See #72
Late escaping on the Configure » Components tab

See #72
Late escape module screen title

See #72
Late escaping for hook Ajax

See #77
Late escaping for the points hooks class

See #77
Late escaping for points hooks

See #77
Late escaping for points logs

See #77
Late escaping for points functions

See #77
Late escaping for widgets

See #77
Late escaping for general functions

See #77
Late escaping for printf() calls

See #77
Pass the second argument to KSES

It’s required.

See #77