display plugin count for each Maven version prerequisite

git-svn-id: https://svn.apache.org/repos/asf/maven/sandbox/trunk@1632737 13f79535-47bb-0310-9956-ffa450edef68
added plugins provided by pulti-module builds (and protect against plugin-info grabbing  problems)

git-svn-id: https://svn.apache.org/repos/asf/maven/sandbox/trunk@1632738 13f79535-47bb-0310-9956-ffa450edef68
display total count of plugins

git-svn-id: https://svn.apache.org/repos/asf/maven/sandbox/trunk@1632739 13f79535-47bb-0310-9956-ffa450edef68