CLN: remove extant uses of built-in filter function

[simonjayhawkins]

No internet for a good part of yesterday so some time to experiment with code cleanups.

[jreback]

thanks @simonjayhawkins if all are removed then pls add a code_check to ban these (may not be easy though); its possible have to use a static analyzer

[simonjayhawkins]

would be a good idea

the regex that I used to find these contained false positives (such as simplefilter) will need to look again I just used [^\.]filter\( to get filter calls that weren't methods

will need to put on todo list.

[simonjayhawkins]

I think (?<!def)[\(\s]filter\( could work