Ability to pick upnp control url

[CDuPlooy]

Sorry for opening this again, in the previous code a check was done for urn:schemas-upnp-org:service:WANIPConnection:1 ; That did not work on my router, I later added a check for a PPPIPConnection:1 and only later realised that the trick was there could be multiple of these strings.

I modified the code so that search_gateway defaults to the first one found, but added a function that can be used to create a Gateway using a particular control url. I tested this in different networks and it worked in those! :)

[CDuPlooy]

Ah I see I didn't change the implementations inside of the aio directory, I'll fix that in a bit.

[sbstp]

Hey, sorrry. I'm busy this week. Don't hesitate to ping me next week if I forget to review this.

[sbstp]

It seems like there's a lack of coherence in this. When I built it I got these warnings:

simon@switch:~/projects/rust-igd$ cargo test --all-features
   Compiling igd v0.9.1 (/home/simon/projects/rust-igd)
warning: function is never used: `get_control_urls`
  --> src/search.rs:51:1
   |
51 | pub fn get_control_urls(options: SearchOptions) -> Result<Vec<String>, SearchError> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: #[warn(dead_code)] on by default

warning: function is never used: `get_gateway_with_control_url`
  --> src/search.rs:76:1
   |
76 | pub fn get_gateway_with_control_url(options: SearchOptions, url: &str) -> Result<Gateway, SearchError>{
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: function is never used: `get_control_urls`
  --> src/search.rs:51:1
   |
51 | pub fn get_control_urls(options: SearchOptions) -> Result<Vec<String>, SearchError> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: #[warn(dead_code)] on by default

warning: function is never used: `get_gateway_with_control_url`
  --> src/search.rs:76:1
   |
76 | pub fn get_gateway_with_control_url(options: SearchOptions, url: &str) -> Result<Gateway, SearchError>{
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

If you want to use these functions as an end user of the library, you should export them publicly. Can you make another PR to rectify this? Ideally I'd like to pick the best device available for this and avoid making the user choose, but I'm not sure how to proceed. I'll look into this further.