Support for ≒ U+2252 and ≓ U+2253

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Adding ≒ eq.fallingdots and ≓ eq.risingdots for U+2252 (Approximately Equal To or the Image Of) and U+2253 (Image of or Approximately Equal To)

In LaTeX package amssymb these two are represented by \fallingdotseq and \risingdotseq.

The former one is also used as an alternative for ≈ (approx) in certain countries and regions (e.g. Japan and Taiwan).