Remove .baseUrl and add a chainable way to append an url

[elbywan]

Example :

// Old way : with baseUrl
const w = wretch().baseUrl("http://prefix.com/data")
w("/1").get()
w("/2").get()
// Oops ...
w.baseUrl("http://prefix.com/data/subdata")("/1").get()

// New way : With a flag ?
const w = wretch("http://prefix.com/data")
w.url("/1", true).get()
w.url("/2", true).get()
w.url("/subdata", true).url("/1", true).get()

// New way : Or with a new method ?
const w = wretch("http://prefix.com/data")
w.addUrl("/1").get()
w.addUrl("/1").get()
w.addUrl("/subdata").addUrl("/1").get()

// Or both ?

// Or simply make .url append instead of replacing urls ?
// My favourite, even if it's a breaking change I feel like it's more intuitive this way

const w = wretch("http://prefix.com/data")
w.url("/1").get()
w.url("/2").get()
w.url("/subdata").url("/1").get()

// With a 'replace' flag
w.url("http://test.com/", true)

[elbywan]

Implemented :

const w = wretch("http://prefix.com/data")
w.url("/1").get() // -> http://prefix.com/data/1
w.url("/2").get() // -> http://prefix.com/data/2
w.url("/subdata").url("/1").get() // -> http://prefix.com/data/subdata/1

// With a 'replace' flag
w.url("http://test.com/", true) // -> http://test.com/

Big syntax improvement over having both the baseUrl + url methods in my opinion !