Support <, >, |, and long-form symbols. Fix #662

Add long-form aliases for various text symbols

* \textgreater is an alias for > in text mode
* \textless is an alias for < in text mode
* \textbar is an alias for | in text mode
* \textdollar is an alias for \$ in text mode
* \textunderscore is an alias for \_ in text mode
* \textbraceleft is an alias for \{ in text mode
* \textbraceright is an alias for \} in text mode
* \textless is an alias for < in text mode
* \textgreater is an alias for > in text mode
* \textbar is an alias for | in text mode
* \textbardbl is an alias for \| in text mode
* \textendash is an alias for -- in text mode
* \textemdash is an alias for --- in text mode
* \textquoteleft is an alias for ` in text mode
* \textquoteright is an alias for ' in text mode
* \textquotedblleft is an alias for `` in text mode
* \textquotedblright is an alias for '' in text mode
* \textdagger is an alias for \dag in text mode
* \textdaggerdbl is an alias for \ddag in text mode
* \textsterling is an alias for \pounds in text mode
* \dag, \ddag work in text mode
* \circledR, \checkmark, \pounds work in text mode too
* Extend Symbols1 test to test \pounds and \textdollar in \text
* Add note about \pounds in text vs. math mode

test/screenshotter/ss_data.yaml

@@ -168,7 +168,7 @@ SupSubLeftAlignReset: |
 SupSubOffsets: \displaystyle \int_{2+3}x f^{2+3}+3\lim_{2+3+4+5}f
 Symbols1: |
     \maltese\degree\pounds\$
-    \text{\maltese\degree}
+    \text{\maltese\degree\pounds\textdollar}
 Text: \frac{a}{b}\text{c~ {ab} \ e}+fg
 Unicode: \begin{matrix}\text{ÀàÇçÉéÏïÖöÛû} \\ \text{БГДЖЗЙЛФЦШЫЮЯ} \\ \text{여보세요} \\ \text{私はバナナです} \end{matrix}
 UnsupportedCmds: