v4.3.4

Attention: revert commit from v4.3.3 [a48aeab5a6] - BEMHTML: should properly render attr values (miripiruni)

Skip mix item if falsy:

// BEMJSON
{
    block: 'b1',
    mix: [ null, '', false, undefined, 0, { block: 'b2' } ]
}
// Will render to:
'<div class="b1 b2"></div>'

Commits:

• [e8e468dce7] - BEMHTML: skip mix item if falsy (miripiruni)