Change doc url

Added URLGit for handling Github URLs which will now use the version of the API running to avoid inconsistencies.

core/src/main/java/com/github/fernthedev/fernapi/universal/Universal.java

@@ -2,6 +2,7 @@
 
 import com.github.fernthedev.fernapi.universal.api.ILocale;
 import com.github.fernthedev.fernapi.universal.api.Locale;
+import com.github.fernthedev.fernapi.universal.api.URLGit;
 import com.github.fernthedev.fernapi.universal.data.network.IPMessageHandler;
 import com.github.fernthedev.fernapi.universal.exceptions.FernRuntimeException;
 import com.github.fernthedev.fernapi.universal.exceptions.setup.IncorrectSetupException;
@@ -11,7 +12,9 @@
 import lombok.NonNull;
 import lombok.Setter;
 
-
+/**
+ * Holds most of the core api
+ */
 public class Universal {
 
     private Universal() {}
@@ -64,7 +67,7 @@ public void setup(@NonNull MethodInterface<?> methodInterface, FernAPIPlugin apl
     protected static void checkNull() {
         if(mi == null || !setup) {
             try {
-                throw new IncorrectSetupException("You have not setup the API correctly. Check this for more info: https://github.com/Fernthedev/FernAPI/blob/master/error/incorrectsetup.md",new NullPointerException());
+                throw new IncorrectSetupException("You have not setup the API correctly. Check this for more info: " + URLGit.INCORRECT_SETUP, new NullPointerException());
             } catch (IncorrectSetupException e) {
                 e.printStackTrace();
             }

core/src/main/java/com/github/fernthedev/fernapi/universal/api/URLGit.java

@@ -0,0 +1,35 @@
+package com.github.fernthedev.fernapi.universal.api;
+
+import lombok.Getter;
+
+/**
+ * Holds URLs for github files that may change in the future.
+ */
+@Getter
+public class URLGit {
+
+    private static final String tag;
+
+    static {
+        Package pack = URLGit.class.getPackage();
+        String checkTag = pack.getSpecificationVersion();
+
+        if (checkTag == null) checkTag = pack.getImplementationVersion();
+        if (checkTag == null) throw new NullPointerException("Version is somehow null. Checked specification and implementation");
+
+        tag = checkTag;
+    }
+
+    public static String formatString(String string) {
+        return string
+                .replaceAll("%tag%", tag);
+    }
+
+    public static final String MAIN_PATH = "https://github.com/Fernthedev/FernAPI/";
+    public static final String FILE_PATH = MAIN_PATH + "blob/%tag%/";
+    public static final String DOCS = FILE_PATH + "docs/";
+
+    public static final String INCORRECT_SETUP = formatString(DOCS + "error/incorrectsetup.md");
+
+
+}