maven-changelog-plugin major rewrite

This is a major rewrite of the maven-changelog-plugin to start tacking the abysmal state that it is in.

I was pretty p*ssed to find out that I have to set a "factory" property when I want to use SVN, that the SVN support only works when the plugin runs in the correct working directory and that the date limitation does not work at all (at least on Linux).

Also the different repository syntax from CVS (why do we have this scm:<scm type>:<scm subtype>:<host>:<repo>:<path> definition if no one cares about it?) is misleading, local URLs like file: or svn+ssh don't seem to work and all in all the whole SVN support is rudimentary at best.

This rewrite tackles the following problems:

• Auto select the SCM type. Look at the second field and choose cvs, clearcase, perforce, starteam, svn.

• do some code cleanup. Juggle a few constants, move a bit of the init code, make token parsing saner.

• bring the SVN code somehow in line with CVS. Repository connections now look like CVS connection:

<repository>scm:svn:http:svn.apache.org:/repos/asf/foo/trunk</repository>

or

<repository>scm:svn:svnssh:henning@svnserver.foo.org:/repos/local/opensource/foo</repository>

• support for all SVN connection types (http, https, file, local, svn, svnssh)

• support for passwords (when using the ";" delimiter):

<repository>scm;svn;http;henning:secret@svn.private.org;/repos/asf/foo/trunk</repository>

• make the svn log actually look at the pom defined repository and not at "current working directory"

• supply username and password to svn if given by the pom

This patch should probably not be applied "as is". It is a patch from our internal SVN to the current SVN head @ apache.
It contains a few changes to e.g. project.xml which shouldn't be applied to the repo (but I'm much too lazy to start sorting out this patch).

If you give me karma for the changelog-plugin I'd even be willing to apply them to the Apache SVN myself.