Hygiene: Use strtr() instead of str_replace() for character swapping

Hygiene: Use strtr() instead of str_replace() for character swapping

strtr() is marginally faster as it runs through the string only
once. A better fit for one-for-one character translation.

The strtr() function also supports an associative array as second
parameter for entire string replacements. This, too, has the same
performance and predictable behaviour (starts with the longest key).
Whereas str_replace is for more aggressive needs where you want
multiple passes until there are no further matches.

The associative array form is arguably also easier to understand
and harder to mess up since the needle/replacement pairs are
explicitly connected instead of two separate arrays.

Also:
* Use getFormattedNsText instead of strtr( getNsText, .. ) which
  reduces duplication of this fact through a more semantic intent.

Change-Id: Ie23e4210a5b6908dd79eebc8a2b931d12fe31af6