Charges change size and centering

[xavierholt]

If the last atom in a SMILES string has a charge, the resulting molecule draws smaller and not quite centered:

[xavierholt]

Actually, this is more likely about the leftmost atom in the drawing rather than the first atom in the input (which does tend to end up on the left). Line ~645 in SvgWrapper.js:

// ... but for direction left move to the right to 
if (direction === 'left' && text[0][0] !== text[0][1]) {
  bbox.width *= 2.0;
}

Atoms in the left direction get a double-width bounding box for some reason, and then this is used a little later to update the bounding box for the whole drawing, pushing things off center.

[xavierholt]

Any fix to this should probably include a fix for #207, and vice versa.