Provide option for user defined coins

[madnight]

@BlkChockr suggested that the user should be able to define any coin in an generic way by adding its code as param

bitcoin-chart-cli --coin ETH

[kroitor]

"use strict";
let coin = null
process.argv.forEach (arg => {
    if (arg.indexOf ('--coin') >= 0)
        coin = arg.split ('=')[1]
})
console.log (coin)

[madnight]

@kroitor thx, i think i need to rewrite it a bit, my linter settings are quite strong (no mutation allowed / only immutable values (const))

[kroitor]

"use strict";
// almost pure functional )
const coin = (process.argv.filter (x => x.indexOf ('--coin') >= 0)[0] || '--coin=default').split ('=')[1]
console.log (coin)

[madnight]

done! version 3.0 released thx to @BlkChockr and @kroitor

[kroitor]

Cool! )