Just reviewing Scrutinizer's list of "bugs". There are 19 ascribed to me. For some, I will definitely take no action (e.g. use of bitwise operators in AND, OR, and XOR functions). However, where I can clean things up so that Scrutinizer is satisfied and the resulting code is not too contorted, I will make an attempt.
This PR corrects 3 problems (2 mine) according to Scrutinizer, and 7 per Phpstan. It also moves the Reader Slk tests under their own directory, as is the case for all the other Reader types.