Remove name mangling? (when creating variables from external sources)

Hey,

Hi!

Currently dots and spaces are converted to underscores when pulling them in
from HTML:

<!-- php will only see two submitted values, b/c of mangling -->
<input type='file' name='file5.1' />
<input type='file' name='file5 1' />
<input type='file' name='file5_1' />
<input type='text' name='file5.1' />
<input type='text' name='file5 1' />
<input type='text' name='file5_1' />

Ostensibly[1], names were mangled to support import_request_variables and
register_globals. But curiously other characters that would create an
invalid variable aren't mangled:

<input type='text' name='file5$1' /> <!-- why not mangle $ also? -->

There are already two bug requests out there asking to remove this behavior
or expose the original name: #34882 and #42055

Since 5.4.0 removed both import_request_variables and register_globals,
does this mangling serve any purpose? If not, can we remove it?

[1] http://php.net/manual/en/language.variables.external.php
[2] https://bugs.php.net/bug.php?id=34882
[3] https://bugs.php.net/bug.php?id=42055

I'm all for this. Mangling has always seemed ...weird... Pulling it
out is awesome.

However, it also would be a pretty non-trivial BC break for people who
rely on the mangling. This would be likely something for 8?

Anthony