Default theme changed to `a` in jQM 1.4

In jQM 1.4, the default theme was changed to `a`.[1]

[1] http://jquerymobile.com/upgrade-guide/1.4/#default-theme
Implemented real controlgroup

In jQM 1.4, there's an official workaround to make controlgroups containing textinputs.[1] This has been implemented in this commit.

[1] http://demos.jquerymobile.com/1.4.3/controlgroup/#Textinputs
Buttons are manually enhances

In jQM 1.4, it's easy to manually enhance buttons, which (marginally) improves performance.[1] This has been implemented in this commit.

[1] http://jquerymobile.com/upgrade-guide/1.4/#buttons