Add characters from Control Pictures block

[Ryan1729]

The Unicode Control Pictures block contains glyphs for displaying otherwise unprintable control characters from ASCII, such as tab or line feed. It is sometimes useful to be able to see which, if any of these characters are contained in a file. If a font has these Control Pictures glyphs then a viewing program can display them instead of those characters. For the first 33 characters this turns out to be a simple addition of 0x2400 to each character below 33.

The most common case where it is useful to see which control characters are present is when a file has been edited with a program which has changed the line endings from windows-style CRLF to unix-style LF or vice-versa. So the ␍ and ␊ characters would probably see the most use. However, in whtespace sensitive languages like Python it can also be useful to see exactly how many spaces and or tabs are on each line of a file.

This issue is similar to #196. That in that issue the question of italicized versions of normally invisible glyphs came up. To my knowledge, most versions of these glyphs are not changed for italic or bold sets, but that may be because on many systems these characters are provided only by symbol heavy fonts.

[chrissimpkins]

Ty! I appreciate this suggestion. I will take a look into this.