Returns true if c is a valid code point
Note that this includes the non-character code points U+FFFE and U+FFFF, since these are valid code points (even though they are not valid characters).
Supersedes: This function supersedes std.utf.startsValidDchar().
the code point to be tested
See Implementation
Unicode 5.0, ASCII, ISO-8859-1, ISO-8859-2, WINDOWS-1250, WINDOWS-1251, WINDOWS-1252
Returns true if c is a valid code point
Note that this includes the non-character code points U+FFFE and U+FFFF, since these are valid code points (even though they are not valid characters).
Supersedes: This function supersedes std.utf.startsValidDchar().