Support Ivy 2.3.0-final.

This entailed modifying ResolutionCache and the CustomPomParser
to reflect changes to the ResolutionCacheManager interface and
DefaultExtendsDescriptor class between Ivy 2.3.0-rc1 and
2.3.0-rc2. Specifically,

1. ResolutionCacheManager now includes two additional methods
that needed implementations in ResolutionCache:
getResolvedModuleDescriptor(mrid: ModuleRevisionId) and
saveResolvedModuleDescriptor(md: ModuleDescriptor). I adapted
the implementations for these (which are expressed primarily in
terms of other interface methods) from Ivy 2.3.0's
DefaultResolutionCacheManager.

2. Instead of taking a ModuleRevisionIdentifier and a resolved
ModuleRevisionIdentifier as its first two arguments, the
DefaultExtendsDescriptor constructor now takes a
ModuleDescriptor. This was a trivial change.

Note that ResolutionCache.getResolvedModuleDescriptor does not
appear to be used by Ivy as sbt uses Ivy and there is thus no
test coverage for its implementation. Also note that the
DefaultResolutionCacheManager object created in
Update.configureResolutionCache now requires a reference to an
IvySettings object; DRCM expects this to be non-null.

ivy/src/main/scala/sbt/CustomPomParser.scala

@@ -203,7 +203,7 @@ object CustomPomParser
 		val unique = IvySbt.mergeDuplicateDefinitions(withExtra)
 		unique foreach dmd.addDependency
 
-		for( ed <- md.getInheritedDescriptors) dmd.addInheritedDescriptor( new DefaultExtendsDescriptor( mrid, resolvedMrid, ed.getLocation, ed.getExtendsTypes) )
+		for( ed <- md.getInheritedDescriptors) dmd.addInheritedDescriptor( new DefaultExtendsDescriptor( md, ed.getLocation, ed.getExtendsTypes) )
 		for( conf <- md.getConfigurations) {
 			dmd.addConfiguration(conf)
 			for(art <- md.getArtifacts(conf.getName)) {

ivy/src/main/scala/sbt/Ivy.scala

@@ -310,7 +310,7 @@ private object IvySbt
 	private[this] def configureResolutionCache(settings: IvySettings, localOnly: Boolean, resCacheDir: Option[File])
 	{
 		val base = resCacheDir getOrElse settings.getDefaultResolutionCacheBasedir
-		settings.setResolutionCacheManager(new ResolutionCache(base))
+		settings.setResolutionCacheManager(new ResolutionCache(base, settings))
 	}
 	// set the artifact resolver to be the main resolver.
 	// this is because sometimes the artifact resolver saved in the cache is not correct

ivy/src/main/scala/sbt/ResolutionCache.scala

@@ -1,18 +1,24 @@
 package sbt
 
 import java.io.File
+import java.io.FileInputStream
+import java.util.Properties
 import org.apache.ivy.core
+import org.apache.ivy.plugins.parser
 import core.IvyPatternHelper
+import core.settings.IvySettings
 import core.cache.{CacheMetadataOptions, DefaultRepositoryCacheManager, DefaultResolutionCacheManager, ResolutionCacheManager}
 import core.module.id.ModuleRevisionId
+import core.module.descriptor.ModuleDescriptor
 import ResolutionCache.{Name, ReportDirectory, ResolvedName, ResolvedPattern}
+import parser.xml.XmlModuleDescriptorParser
 
 /** Replaces the standard Ivy resolution cache in order to:
 * 1. Separate cached resolved Ivy files from resolution reports, making the resolution reports easier to find.
 * 2. Have them per-project for easier cleaning (possible with standard cache, but central to this custom one).
 * 3. Cache location includes extra attributes so that cross builds of a plugin do not overwrite each other.
 */
-private[sbt] final class ResolutionCache(base: File) extends ResolutionCacheManager
+private[sbt] final class ResolutionCache(base: File, settings: IvySettings) extends ResolutionCacheManager
 {
 	private[this] def resolvedFileInCache(m: ModuleRevisionId, name: String, ext: String): File = {
 		val p = ResolvedPattern
@@ -35,6 +41,25 @@ private[sbt] final class ResolutionCache(base: File) extends ResolutionCacheMana
 		new File(reportBase, resolveId + "-" + conf + ".xml")
 	def getConfigurationResolveReportsInCache(resolveId: String): Array[File] =
 		IO.listFiles(reportBase).filter(_.getName.startsWith(resolveId + "-"))
+	
+		// XXX: this method is required by ResolutionCacheManager in Ivy 2.3.0 final,
+		// but it is apparently unused by Ivy as sbt uses Ivy.  Therefore, it is
+		// unexercised in tests.  Note that the implementation of this method in Ivy 2.3.0's
+		// DefaultResolutionCache also resolves parent properties for a given mrid
+		def getResolvedModuleDescriptor(mrid: ModuleRevisionId): ModuleDescriptor = {
+			val ivyFile = getResolvedIvyFileInCache(mrid)
+			if (!ivyFile.exists()) {
+				throw new IllegalStateException("Ivy file not found in cache for " + mrid + "!")
+			}
+		
+			return XmlModuleDescriptorParser.getInstance().parseDescriptor(settings, ivyFile.toURI().toURL(), false)
+		}
+	
+		def saveResolvedModuleDescriptor(md: ModuleDescriptor): Unit = {
+			val mrid = md.getResolvedModuleRevisionId
+			val cachedIvyFile = getResolvedIvyFileInCache(mrid)
+			md.toIvyFile(cachedIvyFile)
+		}
 }
 private[sbt] object ResolutionCache
 {