[vreg] move base registry implementation to logilab.common. Closes #1916014 A new logilab.common.registry module has been created with content from * cw.vreg (the whole things that was in there) * cw.appobject (base selectors and all). In the process, we've done some renaming: * former selector functions are now known as "predicate", though you still use predicates to build an object'selector * hence `objectify_selector` decorator is now `objectify_predicate` * the top level registry is now `RegistryStore` (was `VRegistry`) Also there is no more need for the @lltrace decorator. On the CubicWeb side, the `selectors` module has been renamed to `predicates`. There should be full backward compat with proper deprecation warnings.

function datetuple(d) {
    return [d.getFullYear(), d.getMonth()+1, d.getDate(), 
	    d.getHours(), d.getMinutes()];
}
    
function pprint(obj) {
    print('{');
    for(k in obj) {
	print('  ' + k + ' = ' + obj[k]);
    }
    print('}');
}

function arrayrepr(array) {
    return '[' + array.join(', ') + ']';
}
    
function assertArrayEquals(array1, array2) {
    if (array1.length != array2.length) {
	throw new crosscheck.AssertionFailure(array1.join(', ') + ' != ' + array2.join(', '));
    }
    for (var i=0; i<array1.length; i++) {
	if (array1[i] != array2[i]) {
	    
	    throw new crosscheck.AssertionFailure(arrayrepr(array1) + ' and ' + arrayrepr(array2)
						 + ' differs at index ' + i);
	}
    }
}