PSALM improvements

PSALM si cool, useful project. It will be nice if PSALM could be extended:

a) to have nice output of code analysis - number of errors, warning, notices with option to export to json, xml.

quick workaround is:
cat psalm_output.json | python3.8 -m json.tool | grep "severity" | wc -l

or something similar...

b) with better memory management - with few ten of files it takes around 600MB which is too much.

workaround is to analyze directory by directory
vendor/bin/psalm --config=psalm.xml $directory1 $directory2