Allow specifying run scripts to run right after compilation

With Xcode 10 dependent targets won't start compiling until compilation and all run scripts are done for the target. This means that your run script should run before Copy Files (and Copy Resources, etc.) phases unless it needs to run later, to allow dependent targets to compile faster.

Sources/XcodeGenKit/PBXProjGenerator.swift

@@ -646,6 +646,8 @@ public class PBXProjGenerator {
         let sourcesBuildPhaseFiles = getBuildFilesForPhase(.sources)
         let sourcesBuildPhase = createObject(id: target.name, PBXSourcesBuildPhase(files: sourcesBuildPhaseFiles))
         buildPhases.append(sourcesBuildPhase.reference)
+        
+        buildPhases += try target.postCompileScripts.map { try generateBuildScript(targetName: target.name, buildScript: $0) }
 
         let resourcesBuildPhaseFiles = getBuildFilesForPhase(.resources) + copyResourcesReferences
         if !resourcesBuildPhaseFiles.isEmpty {