Reformat list of math functions

[gmantele]

In his 3rd RFC comment, @msdemlei suggested to transform the two tables listing math functions into lists:

(3) The function tables on p. 16f: I'm in general not a big fan of tables when what something really is is a definition list or perhaps only an enumeration, and I'm almost always encouraging fewer rules within the tables. Perhaps we don't have to convert this in PR, but let's change the function enumerations to some more appropriate format in 2.2.