Added Maven checkstyle plugin.

pom.xml

@@ -216,7 +216,64 @@
           <logViolationsToConsole>true</logViolationsToConsole>
           <checkstyleRules>
             <module name="Checker">
+              <!-- Tabs are strictly banned -->
               <module name="FileTabCharacter"/>
+
+              <module name="TreeWalker">
+                <!-- Important basics -->
+                <!-- <module name="PackageDeclaration"/> Unlikely that we would miss this in a PR -->
+                <module name="OuterTypeFilename"/> <!-- TypeName -> TypeName.java -->
+
+                <!--
+                Control package usage, so people don't insert Bukkit into WE where it shouldn't belong, etc.
+                It is a bit draconian, so update as necessary!
+                -->
+                <module name="ImportControl">
+                  <property name="file" value="${basedir}/src/main/build/import-control.xml"/>
+                </module>
+
+                <!-- Code -->
+                <module name="HideUtilityClassConstructor"/> <!-- Utility classes should not have a constructor -->
+                <module name="CovariantEquals"/>
+                <module name="EqualsHashCode"/> <!-- equals() and hashCode() go together -->
+                <module name="NestedTryDepth"> <!-- SHOULD not need to adjust this -->
+                  <property name="max" value="2"/>
+                </module>
+                <module name="SuperFinalize"/> <!-- We don't actually use this -->
+                <module name="JUnitTestCase"/> <!-- Checks tearDown(), setUp() etc. -->
+
+                <!-- Style -->
+                <module name="LeftCurly"> <!-- Left brace never goes on another line -->
+                  <property name="option" value="eol"/>
+                </module> <!-- We don't check right brance -->
+                <module name="DefaultComesLast"/> <!-- default case in switch should be last -->
+                <module name="GenericWhitespace"/>
+
+                <!-- Naming -->
+                <module name="ClassTypeParameterName">
+                  <property name="format" value="^[A-Z][a-zA-Z0-9]*$"/>
+                </module>
+                <module name="LocalFinalVariableName"/>
+                <module name="LocalVariableName">
+                  <property name="format" value="^[a-z_][a-zA-Z0-9]*$"/>
+                </module>
+                <module name="MemberName">
+                  <property name="format" value="^[a-z_][a-zA-Z0-9]*$"/>
+                </module>
+                <module name="MethodName">
+                  <property name="format" value="^[a-z][a-zA-Z0-9]*$"/>
+                </module>
+                <!-- <module name="PackageName"/> Unlikely that we would miss this in a PR -->
+                <module name="ParameterName"/>
+                <!-- <module name="TypeName"/> Unlikely that we would miss this in a PR -->
+              </module>
+
+              <!-- Require the header, something that many people forget and we hate to fix -->
+              <!-- You should configure the header in your IDE -->
+              <module name="Header">
+                <property name="headerFile" value="${basedir}/src/main/build/header.txt"/>
+                <property name="fileExtensions" value="java"/>
+              </module>
             </module>
           </checkstyleRules>
         </configuration>

src/main/build/import-control.xml

@@ -0,0 +1,51 @@
+<!DOCTYPE import-control PUBLIC
+    "-//Puppy Crawl//DTD Import Control 1.1//EN"
+    "http://www.puppycrawl.com/dtds/import_control_1_1.dtd">
+
+<import-control pkg="com.sk89q">
+  <allow pkg="java"/>
+  <allow pkg="javax"/>
+  <allow pkg="org.junit"/>
+  <allow pkg="org.mockito"/>
+  <allow pkg="com.sk89q"/>
+  <allow pkg="com.google.common"/>
+
+  <subpackage name="util.yaml">
+    <allow pkg="org.yaml.snakeyaml"/>
+  </subpackage>
+
+  <subpackage name="bukkit">
+    <allow pkg="org.bukkit"/>
+  </subpackage>
+
+  <subpackage name="wepif">
+    <allow pkg="org.bukkit"/>
+    <allow pkg="de.bananaco"/>
+    <allow pkg="org.anjocaido"/>
+    <allow pkg="com.nijiko"/>
+    <allow pkg="com.nijikokun"/>
+    <allow pkg="ru.tehkode"/>
+  </subpackage>
+
+  <subpackage name="worldedit">
+    <allow pkg="org.mozilla.javascript"/>
+    <allow pkg="de.schlichtherle"/>
+
+    <subpackage name="bukkit">
+      <allow pkg="org.bukkit"/>
+      <allow pkg="net.minecraft.server"/>
+    </subpackage>
+
+    <subpackage name="spout">
+      <allow pkg="org.spout"/>
+      <allow pkg="org.jboss.netty"/>
+      <allow pkg="org.apache"/>
+    </subpackage>
+
+    <subpackage name="forge">
+      <allow pkg="cpw"/>
+      <allow pkg="net.minecraft"/>
+      <allow pkg="net.minecraftforge"/>
+    </subpackage>
+  </subpackage>
+</import-control>