Switch to maven.

Move files to maven structure, using the following script:

```bash
function do-mv() {
  if [ -f $2 -o -d $2 ]; then
    echo "Already moved: $2"
    return
  fi
  mkdir -p $(dirname $2)
  git mv "$1" "$2"
}

do-mv src/main/mondrian/parser/MdxParser.jj src/main/javacc/mondrian/parser/MdxParser.jj
for i in $(find testsrc -name \*.xml -o -name \*.csv -o -name \*.properties); do
  do-mv $i $(echo $i | sed -e 's!testsrc/main!src/test/resources!')
done
do-mv src/main/META-INF src/main/resources/META-INF
do-mv src/main/OSGI-INF src/main/resources/OSFI-INF
do-mv src/main/mondrian src/main/java/mondrian
do-mv src/main/overview.html src/main/java/overview.html

rmdir testsrc/queryFiles
rmdir testsrc/pendingQueryFiles

do-mv testsrc/main src/test/java
do-mv src/main/mondrian/olap/Mondrian3Schema.xml src/main/xom/mondrian/olap/Mondrian3Schema.xml
do-mv src/main/mondrian/olap/MondrianSchema.xml src/main/xom/mondrian/olap/MondrianSchema.xml
do-mv src/main/mondrian/rolap/aggmatcher/DefaultRules.xml src/main/xom/mondrian/rolap/aggmatcher/DefaultRules.xml
do-mv src/main/mondrian/rolap/aggmatcher/DefaultRulesSchema.xml src/main/xom/mondrian/rolap/aggmatcher/DefaultRulesSchema.xml
do-mv src/main/mondrian/xmla/DataSourcesConfig.xml src/main/xom/mondrian/xmla/DataSourcesConfig.xml
do-mv src/main/mondrian/olap/MondrianProperties.xml src/main/prop/mondrian/olap/MondrianProperties.xml
```

Maven calls out to ant for various code generation tasks. I have changed
build.xml for the new file structure, so I believe that you can use ant
as before, but I haven't checked.

Most tests pass. I haven't checked whether the failure rate is the same as
on lagunitas branch using ant.

Intellij is able to read the pom.xml, populate a workspace, and run tests,
so I have obsoleted Intellij project files.