Split Getdown into multiple (Maven) modules.

- core: the main Getdown logic code
- tools: code to create digest.txt & patch files
- launcher: the standalone launcher/updater app
- ant: the Ant task for creating digest.txt files

This paves the way for a proper Jigsaw-ification of the Getdown code.

I may further factor code out of getdown-launcher and into getdown-core to
enable the use-case where an app embeds Getdown completely and does not use the
launcher app/UI. That will also make it easier to create a JavaFX UI and retire
the old Swing UI.

This also moves the obsolete applet code into a separate applet module, which
is merely a temporary holding area. It will be deleted in the next commit.

core/pom.xml

@@ -0,0 +1,44 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <groupId>com.threerings</groupId>
+    <artifactId>getdown</artifactId>
+    <version>1.7.2-SNAPSHOT</version>
+  </parent>
+
+  <artifactId>getdown-core</artifactId>
+  <packaging>jar</packaging>
+  <name>Getdown Core</name>
+  <description>Core Getdown functionality</description>
+
+  <dependencies>
+    <dependency>
+      <groupId>com.samskivert</groupId>
+      <artifactId>samskivert</artifactId>
+      <version>1.2</version>
+    </dependency>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.8.1</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-core</artifactId>
+      <version>1.10.19</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <resources>
+      <resource> <!-- include the LICENSE file in the jar -->
+        <directory>..</directory>
+        <includes><include>LICENSE</include></includes>
+      </resource>
+    </resources>
+  </build>
+
+</project>