scalariform should be idempotent

[paulp]

It is useful to have a canonical source representation; it is less useful if the program does not generate it on the first try. I have to run scalariform two additional times on scala trunk before it reaches a fixpoint. It seems the issue is limited to the handling of scaladoc comments; with it so close, it seems a shame not to take it all the way.

These are my settings:

java -jar $JAR \
  -s=2.10.0 \
  +alignSingleLineCaseStatements \
  +alignParameters \
  +compactControlReadability \
  +doubleIndentClassDeclaration \
  +multilineScaladocCommentsStartOnFirstLine \
  +spacesWithinPatternBinders \
  +formatXml \
  -alignSingleLineCaseStatements.maxArrowIndent=40 \
  -indentSpaces=2 \
  -r src

Here is the essence of the diff after the first iteration:

-/**   Used as the timeout pattern in
+/**  Used as the timeout pattern in
-  /**
-   *  A full type-flow analysis on a method computes in- and out-flows for each basic block (that's what MethodTFA does).
+  /** A full type-flow analysis on a method computes in- and out-flows for each basic block (that's what MethodTFA does).
-    /**
-     *  This method is invoked after one or more inlinings have been performed in basic blocks whose in-flow is non-bottom (this makes a difference later).
+    /** This method is invoked after one or more inlinings have been performed in basic blocks whose in-flow is non-bottom (this makes a difference later).
-/**
- *  @author Stephane Micheloud
+/** @author Stephane Micheloud
-/**
- *  @author Stephane Micheloud
+/** @author Stephane Micheloud
-/**  A collection of implicit conversions supporting interoperability between
+/** A collection of implicit conversions supporting interoperability between
-  /**  The erasure |T| of a type T. This is:
+  /** The erasure |T| of a type T. This is:
-/**
- *  SourceFile_attribute {
+/** SourceFile_attribute {

And the second.

-/**  Used as the timeout pattern in
+/** Used as the timeout pattern in

Ah, the second makes me realize what at least part of the problem is. If I add a little whitespace, we see this revealing diff on what would be the next iteration of many.

-/**                     Used as the timeout pattern in
+/**                    Used as the timeout pattern in