fix(inputs): use min-height instead of height

Varying size inputs were using fixed height, but input wrappers
should have flexible height, so they can adjust to the height of a
textarea, for example.
fix(inputs): allow sized and input wrappers in combination

Sized inputs were not working properly together with input wrappers.
This commit allows them to be combined by fixing the placement of
inner controls and their padding.
fix(inputs): use right styles for wrapper placeholder
style(inputs.less): use spaces between mixin args
style(inputs.less): fix comment reference