Currently a bit limited, unfortunately printf's `%a` specifier is
absolutely unreadable.
So we add `hex` and `octal` with `0x` and `0` prefixes respectively,
and also take a number but currently only allow 16 and 8.
The output is truncated to integer, so scale values other than 0 are
invalid and 0 is implied.
The docs mention this may change.
This was typically overridden by "too many/few arguments", but it's
actually incorrect:
sin(55
has the correct number of arguments to `sin`, but it's lacking
the closing `)`.
Just as `math "bitand(5,3)"` and `math "bitor(6,2)"`.
These cast to long long before doing their thing,
so they truncate to an integer, producing weird results with floats.
That's to be expected because float representation is *very*
different, and performing bitwise operations on floats feels quite useless.
Fixes#7281.
It's now good enough to do so.
We don't allow grid-alignment:
```fish
complete -c foo -s b -l barnanana -a '(something)'
complete -c foo -s z -a '(something)'
```
becomes
```fish
complete -c foo -s b -l barnanana -a '(something)'
complete -c foo -s z -a '(something)'
```
It's just more trouble than it is worth.
The one part I'd change:
We align and/or'd parts of an if-condition with the in-block code:
```fish
if true
and false
dosomething
end
```
becomes
```fish
if true
and false
dosomething
end
```
but it's not used terribly much and if we ever fix it we can just
reindent.
Until now, something like
`math '7 = 2'`
would complain about a "missing" operator.
Now we print an error about logical operators not being supported and
point the user towards `test`.
Fixes#6096
