Amend last fix. Fix tooltip misalignment issue when spanned over
text that has a `display' property which alters the text's displayed
dimensions (such as `preview-latex-mode').

* company.el:

(company--create-line-overlay): Don't move point unnecessarily.

(company-pseudo-tooltip-show): Match
`company-pseudo-tooltip-overlay' to cover exactly the lines occupied
by the tooltip, use it to override the region's `display'
property. Recenter buffer overlays before creating tooltip overlays
to supposedly improve performance.