add @ for command names in XML attributes

[Patrice Dumas]

Hello,

You made me use @ in <itemformat command="@minus">..., should I also
do it in the following cases:

<click command="arrow"/>
<entry command="tab"> ...
<indexcommand command="fooindex">...
(with raise/lowersection)
<section originalcommand="chapter"> ...
<clickstyle command="result">
<infoenclose command="a" begin=":" end=":">...

-- 
Pat