Fix indentation of compilation results on the console

Fix indentation of compilation results on the console

Whenever warnings or errors were printed via CompilationResult.toString,
indirectly also using MessageUtil.renderMessage(IMessage, boolean),
messages containing context info such as code snippets with carets
marking erroneous tokens - see also the previous commit - prefixes like
"[warning 1] warning at " were printed right in front of the code
snippets. I.e., the carets marking erroneous tokens in the second line
were not indented like the first line with the code snippet, leading to
(simplified) output like:

  [warning 1] warning at after() : execution(FooBar Blah.*()) {
                      ^^^^^^
  xxx FooBar [Xlint:invalidAbsoluteTypeName]

This was fixed to now correctly indent lines 2 to n according to line 1,
yielding the correct output:

  [warning 1] warning at
              after() : execution(FooBar Blah.*()) {
                                  ^^^^^^
              xxx FooBar [Xlint:invalidAbsoluteTypeName]

Especially with longer, more complex context lines, this helps to
identify the erroneous section. BTW, for one-line messages, everything
of course looks like before.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>