This script was broken by the changes to profiling output in
9d904e1113.
The new version works with both the old and new profiling output, even when
mixed. The script output has been adjusted to match the new profiling style
better.
This also adds basic error handling for situations where the script is invoked
incorrectly and makes the file executable.
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.
Came in handy for tracking down the performance regression in #5219. This will
take the output of two (necessarily identical) `fish --profile ...` runs and
produce a third profile log in which all times are the difference between the
first and the second profile provided.
(I'm not sure if build_tools is the right place for it, but I think it's OK?)
