Member assignment instead of using settings

[daniestevez]

The parameters for some blocks are being done with direct member assignment instead of using the settings because of problems with some types when passing settings. The affected blocks are:

• Vector Source, because sometimes it is used for Pdu<T> types, which cannot be converted to PMT, and because the tags parameter cannot be converted to PMT either (gr::Tag cannot be converted to PMT).
• Mapper, because std::vector<std::complex<float>> cannot be passed to settings, even though it can be converted to PMT.

[daniestevez]

Mapper, because std::vector<std::complex<float>> cannot be passed to settings, even though it can be converted to PMT.

This is now solved, but the Vector Source issue persists.