Standardize info messages when opening the REPL

[jurgenvinju]

Is your feature request related to a problem? Please describe.

This is a typical info dump when the REPL starts:

Rascal 0.41.0-RC47-SNAPSHOT
Rascal search path:
- |std:///|
- |file:///Users/jurgenv/git/rascal/src/org/rascalmpl/compiler|
- |file:///Users/jurgenv/git/rascal/src/org/rascalmpl/tutor|
- |file:///Users/jurgenv/git/rascal/test/org/rascalmpl/test/data|
- |file:///Users/jurgenv/git/rascal/test/org/rascalmpl/benchmark|
- |mvn://org.rascalmpl--typepal--0.15.1| 
Rascal classloader path:
- |file:///Users/jurgenv/git/rascal/target/rascal-0.41.0-RC47-SNAPSHOT.jar|
PathConfig messages:
[WARNING] /Users/jurgenv/.m2/repository/org/apache/commons/commons-math/2.2/commons-math-2.2.pom:0:0: 'build.plugins.plugin.version' for org.apache.maven.plugins:maven-idea-plugin is missing.
[INFO]    /Users/jurgenv/git/rascal/:0:0: Rascal version:0.41.0-RC47-SNAPSHOT
[INFO]    /Users/jurgenv/git/rascal/pom.xml:0:0: Detected Rascal project self-application
rascal>import lang::rascalcore::check::Checker;
ok

Some of it is stdout.println, some of it is Messages.report.

Since we cannot avoid Messages.report, let's report all information via an INFO message.

INFO Messages do not have clean support for multiline messages yet, which is useful for the search paths. That should be added.