Grand refactoring of the scripting DSL + many minor usability refactorings around it

libraries/scripting/common/src/kotlin/script/experimental/host/BasicScriptingHost.kt

@@ -31,8 +31,8 @@ abstract class BasicScriptingHost(
 
     open fun eval(
         script: ScriptSource,
-        compileConfiguration: ScriptCompileConfiguration,
-        environment: ScriptEvaluationEnvironment
+        compileConfiguration: ScriptCompileConfiguration?,
+        environment: ScriptEvaluationEnvironment?
     ): ResultWithDiagnostics<EvaluationResult> =
         runInCoroutineContext {
             compiler(script, scriptDefinition, compileConfiguration).onSuccess {

libraries/scripting/common/src/kotlin/script/experimental/host/scriptHostUtil.kt

@@ -7,7 +7,11 @@ package kotlin.script.experimental.host
 
 import java.io.File
 import java.net.URL
-import kotlin.script.experimental.api.*
+import kotlin.script.experimental.api.ScriptCompileConfiguration
+import kotlin.script.experimental.api.ScriptSource
+import kotlin.script.experimental.api.ScriptSourceNamedFragment
+import kotlin.script.experimental.api.sourceFragments
+import kotlin.script.experimental.util.getOrNull
 
 fun ScriptSource.getScriptText(): String = when {
     text != null -> text!!
@@ -16,9 +20,9 @@ fun ScriptSource.getScriptText(): String = when {
     else -> throw RuntimeException("unable to get text from null script")
 }
 
-fun getMergedScriptText(script: ScriptSource, configuration: ScriptCompileConfiguration): String {
+fun getMergedScriptText(script: ScriptSource, configuration: ScriptCompileConfiguration?): String {
     val originalScriptText = script.getScriptText()
-    val sourceFragments = configuration.getOrNull(ScriptCompileConfigurationProperties.sourceFragments)
+    val sourceFragments = configuration?.getOrNull(ScriptCompileConfiguration.sourceFragments)
     return if (sourceFragments == null || sourceFragments.isEmpty()) {
         originalScriptText
     } else {