Only allow names and enforces capitalization.
Allows letters, spaces, and ' (apostrophe). A character after a space is automatically made upper case. A character not after a space is automatically made lowercase. A character after an apostrophe can be either upper or lower case. Only one apostrophe in the string is allowed. More than one space in a row is not allowed.
A characters is considered a letter if it is categorized as a Unicode letter, as implemented by the Char.Isletter method in .Net.