Primerdriver

Changes:
- Primer characterization
- Complementary DNA-based primer design
- interactive mode only

This pre-release includes the following changes:
- Renamed project from `primerx` to `primerdriver`
- The CLI now consists of several files/submodules. Thus, the file structure has been changed to modular type Python style. Please preserve file structure when extracting to a local machine.
- Primer characterization is now fully functional for both interactive and single-command mode.

Initial release of `primerx` script with very basic functionality and minimal error checking.