Bump samskivert, Depot, Guava to latest releases.

Also update compiler plugin, & add javadoc 8 sanity preserving args.

pom.xml

@@ -45,17 +45,17 @@
     <dependency>
       <groupId>com.samskivert</groupId>
       <artifactId>samskivert</artifactId>
-      <version>1.7.1</version>
+      <version>1.9</version>
     </dependency>
     <dependency>
       <groupId>com.samskivert</groupId>
       <artifactId>depot</artifactId>
-      <version>1.7-SNAPSHOT</version>
+      <version>1.7</version>
     </dependency>
     <dependency>
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
-      <version>14.0.1</version>
+      <version>18.0</version>
     </dependency>
     <dependency>
       <groupId>javax.servlet</groupId>
@@ -76,15 +76,18 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
-        <version>2.3.2</version>
+        <version>3.1</version>
         <configuration>
           <source>1.6</source>
           <target>1.6</target>
           <fork>true</fork>
           <showDeprecation>true</showDeprecation>
           <showWarnings>true</showWarnings>
-          <!-- yes, those quoted spaces are a workaround sanctioned by the Maven idiocracy -->
-          <compilerArgument>-Xlint" "-Xlint:-serial" "-Xlint:-path</compilerArgument>
+          <compilerArgs>
+            <arg>-Xlint</arg>
+            <arg>-Xlint:-serial</arg>
+            <arg>-Xlint:-path</arg>
+          </compilerArgs>
         </configuration>
       </plugin>
       <plugin>
@@ -98,10 +101,11 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-javadoc-plugin</artifactId>
-        <version>2.7</version>
+        <version>2.9.1</version>
         <configuration>
           <quiet>true</quiet>
           <show>public</show>
+          <additionalparam>-Xdoclint:all -Xdoclint:-missing</additionalparam>
           <links>
             <link>http://samskivert.github.com/samskivert/apidocs/</link>
             <link>http://docs.guava-libraries.googlecode.com/git/javadoc/</link>