A bunch of deprecations before reducing functions visibility

[phsym]

As stated in #87, deprecated a few functions before changing their visibility to private

[codecov]

Codecov Report

Merging #88 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #88   +/-   ##
=======================================
  Coverage   84.42%   84.42%           
=======================================
  Files           5        5           
  Lines        1220     1220           
=======================================
  Hits         1030     1030           
  Misses        190      190

Impacted Files	Coverage Δ
src/format.rs	68.72% <ø> (ø)	⬆️
src/cell.rs	85.58% <ø> (ø)	⬆️
src/row.rs	90.96% <ø> (ø)	⬆️
src/lib.rs	86.32% <ø> (ø)	⬆️

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