Repair various issues with modernize-avoid-bind

Repair various issues with modernize-avoid-bind

In the process of running this check on a large codebase I found a
number of limitations, and thought I would pass on my fixes for
possible integration upstream:

* Templated function call operators are not supported
* Function object constructors are always used directly in the lambda
  body, even if their arguments are not captured
* Placeholders with namespace qualifiers (std::placeholders::_1) are
  not detected
* Lambda arguments should be forwarded to the stored function
* Data members from other classes still get captured with this
* Expressions (as opposed to variables) inside std::ref are not captured
  properly
* Function object templates sometimes have their template arguments
  replaced with concrete types

This patch resolves all those issues and adds suitable unit tests.