Add onMapInitializeEvent listener to automatically update map, fix plugin.yml dependency missing, add build instructions to readme

[ryanalexmartin]

BlueMap not being added as a dependency was causing the plugin load order to be wrong:

[17:18:44 ERROR]: [ModernPluginLoadingStrategy] Could not load plugin 'BlueMapMCMapSync-0.1.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: Exception initializing main class `com.technicjelle.bluemapmcmapsync.BlueMapMCMapSync'
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:106) ~[paper-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        at io.papermc.paper.plugin.provider.type.spigot.SpigotPluginProvider.createInstance(SpigotPluginProvider.java:123) ~[paper-1.20.2.jar:git-Paper-318]
        at io.papermc.paper.plugin.provider.type.spigot.SpigotPluginProvider.createInstance(SpigotPluginProvider.java:35) ~[paper-1.20.2.jar:git-Paper-318]
        at io.papermc.paper.plugin.entrypoint.strategy.modern.ModernPluginLoadingStrategy.loadProviders(ModernPluginLoadingStrategy.java:116) ~[paper-1.20.2.jar:git-Paper-318]
        at io.papermc.paper.plugin.storage.SimpleProviderStorage.enter(SimpleProviderStorage.java:38) ~[paper-1.20.2.jar:git-Paper-318]
        at io.papermc.paper.plugin.entrypoint.LaunchEntryPointHandler.enter(LaunchEntryPointHandler.java:36) ~[paper-1.20.2.jar:git-Paper-318]
        at org.bukkit.craftbukkit.v1_20_R2.CraftServer.loadPlugins(CraftServer.java:514) ~[paper-1.20.2.jar:git-Paper-318]
        at net.minecraft.server.dedicated.DedicatedServer.initServer(DedicatedServer.java:273) ~[paper-1.20.2.jar:git-Paper-318]
        at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1086) ~[paper-1.20.2.jar:git-Paper-318]
        at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:315) ~[paper-1.20.2.jar:git-Paper-318]
        at java.lang.Thread.run(Thread.java:1583) ~[?:?]
Caused by: java.lang.reflect.InvocationTargetException
        at jdk.internal.reflect.DirectConstructorHandleAccessor.newInstance(DirectConstructorHandleAccessor.java:74) ~[?:?]
        at java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:502) ~[?:?]
        at java.lang.reflect.Constructor.newInstance(Constructor.java:486) ~[?:?]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:98) ~[paper-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        ... 10 more
Caused by: java.lang.NoClassDefFoundError: de/bluecolored/bluemap/api/BlueMapAPI
        at com.technicjelle.bluemapmcmapsync.BlueMapMCMapSync.<init>(BlueMapMCMapSync.java:61) ~[BlueMapMCMapSync-0.1.jar:?]
        at jdk.internal.reflect.DirectConstructorHandleAccessor.newInstance(DirectConstructorHandleAccessor.java:62) ~[?:?]
        at java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:502) ~[?:?]
        at java.lang.reflect.Constructor.newInstance(Constructor.java:486) ~[?:?]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:98) ~[paper-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        ... 10 more
Caused by: java.lang.ClassNotFoundException: de.bluecolored.bluemap.api.BlueMapAPI
        at org.bukkit.plugin.java.PluginClassLoader.loadClass0(PluginClassLoader.java:197) ~[paper-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        at org.bukkit.plugin.java.PluginClassLoader.loadClass(PluginClassLoader.java:164) ~[paper-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        at java.lang.ClassLoader.loadClass(ClassLoader.java:526) ~[?:?]
        at com.technicjelle.bluemapmcmapsync.BlueMapMCMapSync.<init>(BlueMapMCMapSync.java:61) ~[BlueMapMCMapSync-0.1.jar:?]
        at jdk.internal.reflect.DirectConstructorHandleAccessor.newInstance(DirectConstructorHandleAccessor.java:62) ~[?:?]
        at java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:502) ~[?:?]
        at java.lang.reflect.Constructor.newInstance(Constructor.java:486) ~[?:?]
        at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:98) ~[paper-api-1.20.2-R0.1-SNAPSHOT.jar:?]
        ... 10 more
[17:18:44 INFO]: [BlueMap] Loading server plugin BlueMap v3.20
[17:18:44 INFO]: Server permissions file permissions.yml is empty, ignoring it

Adding BlueMap as a dependency in plugin.yml fixes this.

Also, I added the build instructions to the readme. Feel free to delete that change from this pull request.

[TechnicJelle]

Could you edit the readme to explain the new config option, too?

[ryanalexmartin]

Yes, of course