Replace some [BR] in help texts with rst literals

Replace some [BR] in help texts with rst literals

[BR] cannot really be implemented in rst, so replace those [BR]
instances that were used to implement literal blocks with rst literal
blocks.  Refactor the help output formatting such that line breaks in
the input string get transfered literally to rst output, and make the
console output aware of the line breaks in the input string so that it
can do wrapping as required.  Fix cases that do not produce valid rst
now that leading whitespaces are no longer stripped.

As a side effect of this change, remaining [BR] instances in the help
are now somewhat uglier in the console output, but that can hopefully be
fixed in the future.  On the other hand, the literal blocks look much
nicer on the html and man pages.

Change-Id: If67106c74f84de04d55a2e8c300949c5a297f909