Add orientation on tag glyphs?

[cannin]

It would easier to know if to draw to left or right if this had an orientation

    <glyph id="glyph20" class="tag">
      <label text="ERK"/>
      <bbox x="760.2777022450305" y="423" w="60" h="30"/>
    </glyph>

[adrienrougny]

There's already an optional orientation attribute for the glyph element. It could perhaps be made required when the glyph is a tag or a submap terminal.