New in version 2.5.
Capitalize string:
abjad> string = 'violin I'
abjad> iotools.capitalize_string_start(string)
'Violin I'
Function differs from built-in string.capitalize().
This function affects only string[0] and leaves noninitial characters as-is.
Built-in string.capitalize() forces noninitial characters to lowercase.
abjad> string.capitalize() ‘Violin i’
Return newly constructed string.