Adds the ability to rename inference rules when Tex filtering.

[heades]

Originally, Ott did not allow one to easily rename an inference rule
in Tex. For example, in an Ott specification one might define a rule
like the following:

G, x : A |- t : B
-------------------- :: Fun
G |- \x:A.t : A -> B

Unfortunately, Ott does not provide any means of giving a Tex version of
the name "Fun".

Given the previous rule Ott would generate the following LaTex
(assuming no prefix was given to Ott, and that the judgment prefix is
"T_"):

\newcommand{\OttdruleTXXFun}[1]{\Ottdrule[#1]{%
\Ottpremise{\Gamma \Ottsym{,}  \mathit{x}  \Ottsym{:}  \Ottnt{A}  \vdash  \Ottnt{t}  \Ottsym{:}  \Ottnt{B}}%
}{
\Gamma \vdash   \lambda  \mathit{x}  :  \Ottnt{A} . \Ottnt{t}   \Ottsym{:}  \Ottnt{A}  \to  \Ottnt{B}}{%
{\Ottdrulename{T\_Fun}}{}%
}}

We can see that the name of the rule "T_Fun" is not easily changed within LaTex.

We fix this issue by having Ott factor out the name of each rule into
a constant LaTex command that can be renewed in LaTex. Now given the
rule above Ott will generate the following:

\newcommand{\OttRenameRuleTXXFun}[0]{\Ottdrulename{T\_Fun}}
\newcommand{\OttdruleTXXFun}[1]{\Ottdrule[#1]{%
\Ottpremise{\Gamma \Ottsym{,}  \mathit{x}  \Ottsym{:}  \Ottnt{A}  \vdash  \Ottnt{t}  \Ottsym{:}  \Ottnt{B}}%
}{
\Gamma \vdash   \lambda  \mathit{x}  :  \Ottnt{A} . \Ottnt{t}   \Ottsym{:}  \Ottnt{A}  \to  \Ottnt{B}}{%
{\OttRenameRuleTXXFun}{}%
}}

Then to rename the rule we can simply add the following after the Ott
generated LaTex include file has been importanted:

\renewcommand{\OttRenameRuleTXXFun}[0]{$\rightarrow_I$}

I felt that this modification was the least problematic when it comes
to backward compatibility.

[starsandspirals]

I was just wondering whether there has been any update on the possibility of getting this merged in? It looks like the issues discussed in #62 have been resolved, as far as I can tell.