More Ant builds

Since the Scala compiler is a pretty heavy process to run in buildfiles where it is not needed, I've nested it within a conditional to only run when the Scala library is in the classpath.

My new build macro looks like this:

    <macrodef name="build">
        <attribute name="srcdir"/>
        <attribute name="builddir"/>
        <sequential>
            <mkdir dir="@{builddir}" />
            <javac srcdir="@{srcdir}" 
                destdir="@{builddir}"
                source="${compile.source}"
                target="${compile.target}"
                deprecation="${compile.deprecation}"
                debug="${compile.debug}">
                <classpath refid="classpath" />
            </javac>
            
            <if>
                <available classpathref="classpath" classname="scala.ScalaObject"/>
                <then>
                    <scalac srcdir="@{srcdir}"
                                    destdir="@{builddir}"
                                    classpathref="classpath" />   
                </then>   
            </if>   

            <copy todir="@{builddir}">
                <fileset dir="@{srcdir}">
                    <include name="**/*"/>
                    <exclude name="**/*.java" />
                    <exclude name="**/*.scala" />   
                    <exclude name="**/.svn/*" />
                </fileset>
            </copy>
        </sequential>
    </macrodef>

We also need to define the scalac task like so:

    <taskdef resource="scala/tools/ant/antlib.xml">
        <classpath>
            <pathelement location="ant/jars/scala-compiler.jar" />    
        </classpath>
    </taskdef>