When CDT is not included in the project (ie. we just have Python and/or Java) the current implementation would not create automatically a call to waf
for the build stage. This patch adds in such cases an external builder that automates the call to waf without the need to manually configure one.
added support to search and add into source path also generated source
files for both java and python. this is useful when using generated code
(ie. protoc and pyqt5) so browsing in eclipse works correclty adding also
paths where generated code is done.
extended example in playground demostrating generated code
