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/repl/analyzeErrors.repl

@@ -1,5 +1,7 @@
 >>> fun foo() = 765
 >>> foo(1)
-ERROR: /line2.kts: (1, 5) Too many arguments for internal final fun foo(): kotlin.Int defined in <script>
+/line2.kts:1:5: error: too many arguments for internal final fun foo(): kotlin.Int defined in <script>
+foo(1)
+    ^
 >>> foo()
 765

compiler/testData/repl/objects/localObject.repl

@@ -2,4 +2,6 @@
 ...   object Bar {
 ...   }
 ... }
-ERROR: /line4.kts: (2, 1) Named object 'Bar' is a singleton and cannot be local. Try to use anonymous object instead
+/line4.kts:2:1: error: named object 'Bar' is a singleton and cannot be local. Try to use anonymous object instead
+object Bar {
+^

compiler/testData/repl/syntaxErrors.repl

@@ -1,6 +1,10 @@
 >>> )(
-ERROR: /line1.kts: (1, 1) Expecting an element
-ERROR: /line1.kts: (1, 3) Expecting an expression
+/line1.kts:1:1: error: expecting an element
+)(
+^
+/line1.kts:1:3: error: expecting an expression
+)(
+  ^
 >>> fun foo() = 98
 >>> foo()
 98