Add BPSK/QPSK modulation and demodulation support

[garbagetrash]

I've listed some probable steps for the signal chain below.

Write basic BPSK modulator:

• Random bits
• Upsampling and pulse shaping

Write beginning of a channel impairments block:

• Constant frequency shift
• Constant integer delay
• Constant phase shift

Write basic BPSK demodulator:

• CFO estimator
• Matched filter
• Resampling
• Sample timing recovery
• Symbols to bits