[Protocol] Add GameSpy 3 support. (#25)

* [Protocol] Gamespy3 initial code

* [Protocol] Add rest of challenge solving

* [Protocol] Remove unused stuff

* [Protocol] Remove adding unused bytes

* [Protocol] Clean up code

* [Protocol] Make gs3 a struct

* [Protocol] Add initial key-value parsing

* [Protocol] Manage multiple packets

* [Protocol] Split server vars and other vars

* Revert "[Protocol] Split server vars and other vars"

This reverts commit 9a930aeb68802fcf3d0908a2e031dfea054d37d0.

* [Protocol] Proper packet management and initial response struct

* [Protocol] Fix players_minimum

* [Protocol] Fix server vars to parse only the first packet

* [Protocol] Update CHANGELOG.md

* [Protocol] Initial player parsing

* [Protocol] Split GS one and three

* [Protocol] Add common code file

* [Protocol] Change static to const

* [Protocol] Fix players_online and break on data to map on empty key

* [Protocol] Remove unused types and printlns

* [Protocol] Add teams parsing

* [Protocol] Split key_values and parsing data

* [Crate] Update PROTOCOLS.md

src/bufferer.rs

@@ -108,6 +108,18 @@ impl Bufferer {
         Ok(value)
     }
 
+    pub fn get_string_utf8_optional(&mut self) -> GDResult<String> {
+        match self.get_string_utf8() {
+            Ok(data) => Ok(data),
+            Err(e) => {
+                match e {
+                    PacketUnderflow => Ok(String::new()),
+                    x => Err(x),
+                }
+            }
+        }
+    }
+
     pub fn get_string_utf8_unended(&mut self) -> GDResult<String> {
         let sub_buf = self.remaining_data();
         if sub_buf.is_empty() {