v1.4.0 — Modulation calculator

New features:
- AM/FM/digital modulation bandwidth calculations
- Symbol rate / bit rate conversions
- Spectral efficiency analysis
- Modulation scheme comparison tables
- Support for BPSK, QPSK, 8PSK, 16QAM, 32QAM, 64QAM, 128QAM, 256QAM

Full changelog in commit message.