xubuntu 18.04 gnuplot windows take focus and use 100% cpu so you cant break out ^C

[osde8info]

$ luaradio examples/rtlsdr_wbfm_mono.lua 102.2e6

gnuplot windows take focus and use 100% cpu so you cant break out ^C

i will try and create a PR with a switch to enable gnuplot (with a default of off)

$ luaradio --platform
luajit LuaJIT 2.1.0-beta3
os Linux
arch x64
page size 4096
cpu count 1
cpu model Intel(R) Core(TM) i5 CPU M 540 @ 2.53GHz
features
fftw3f true fftw-3.3.7-sse2-avx
volk true 1.3 (sse4_2_64_mmx_orc)
liquid false

$ luaradio --version
LuaRadio 0.6.0 - Vanya A. Sergeev. https://luaradio.io

[vsergeev]

Closing as duplicate of #26. I think it would be best to consolidate the discussion there.