tests: significantly improved Nette\Forms tests
Form: DefaultFormRenderer do not puts &nbsp; in empty <td></td> or <th></th>

It was needed to display empty cells in <table border=1> in old quirks browser modes
Forms: fixed cutting strings according to Form::LENGTH
Html: setText(Html $el) do not double-escapes $el
Forms: Html elements are not "translated"
Forms: Checkboxes are rendered as <label><input type=checkbox>Label</label> instead of <input type=checkbox><label>Label</label> (BC break!)

In fact, checkboxes are always rendered together with label. So now there is no need to use conditions to render checkboxes (i.e in components\form.latte in Sandbox) and new code is compatible with Twitter Bootstrap etc.
Forms: Radio inputs are rendered as <label><input type=radio>Label</label> instead of <input type=radio><label>Label</label> (BC break!)

Radiolist is rendered the same way as checkboxes and the new generated HTML code is better compatible with Twitter Bootstrap etc.
This commit also reverts support for {label name:$key} (commit 8ab9dfc) because this is not needed now.
Latte: added support for {input name:$key:$label}
ComponentModel\Container::getComponent: empty $name does not throw exception whether $need is FALSE
Forms: fixed #06199805, it ignores empty query parameters