CLI: improve diagnostic message format

- render the whole line where the error/warning points to, if any, and another
  line with '^', like other compilers do
- lowercase diagnostic severity
- decapitalize the message if it doesn't start with a proper name

compiler/testData/integration/ant/jvm/additionalArguments/build.log.expected

@@ -5,7 +5,7 @@ build:
   [kotlinc] Compiling [[TestData]/hello.kt] => [[Temp]/hello.jar]
     [javac] Compiling 1 source file to [Temp]
     [javac] Compiling [[TestData]] => [[Temp]]
-    [javac] INFO: Kotlin Compiler version [KotlinVersion]
+    [javac] info: Kotlin Compiler version [KotlinVersion]
     [javac] Running javac...
 
 BUILD SUCCESSFUL