improved main help and added usage examples
improved main help and added usage examples

bw2/gemini,arq5x/gemini,udp3f/gemini,brentp/gemini,heuermh/gemini,bw2/gemini,bpow/gemini,bpow/gemini,arq5x/gemini,xuzetan/gemini,arq5x/gemini,bgruening/gemini,xuzetan/gemini,bw2/gemini,bgruening/gemini,brentp/gemini,udp3f/gemini,heuermh/gemini,brentp/gemini,udp3f/gemini,heuermh/gemini,udp3f/gemini,heuermh/gemini,bw2/gemini,xuzetan/gemini,brentp/gemini,bpow/gemini,bpow/gemini,bgruening/gemini,bgruening/gemini,arq5x/gemini,xuzetan/gemini