Add .mailmap

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
t0111: Prepare for other filter prefixes

* Validate the email filter by manipulating stdin. Additional checks for
  all the arguments can be added in a later patch.

* Add the exec prefix to all informational messages.

* Rename the filter repository to filter-exec. The Git repository itself
  is not renamed since it can be shared amongst all filter types.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
t0111: Add basic tests for Lua filters

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
t0111: Check all arguments

In the filter checks, check whether all arguments are passed properly
instead of validating the buffer/stdin only.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>