On unidirectional roads lanes count doesn't change to 1

[YaroShkvorets]

When you change number of lanes via "Number of Lanes" edit box and change it to "1" plugin doesn't change the lanes tag to "1". See:

[yrtimiD]

Change from 2 to 1 is applied only after selecting one of direction buttons,
but unselecting direction while lanes == 1 doesn't remove turn:lanes key.