NO-JIRA: Minor API improvements

- Message constructor keyword args.
- Added inferred docstring from C API doc.
- Error checking in subscribe()

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1600528 13f79535-47bb-0310-9956-ffa450edef68
PROTON-592: Use os.linesep in assert test so test passes on Windows.



git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1600676 13f79535-47bb-0310-9956-ffa450edef68
PROTON-596: Add config.bat environment settings for windows.
* Bug-for-bug compatible with config.sh 
** adds new paths after old paths
** uses fixed \build folder for builds
* For use with debug builds only (pending conversion to cmake configure .in file)
To use:
  > cd proton
  > call config.bat
  > cd build
  > ctest


git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1600727 13f79535-47bb-0310-9956-ffa450edef68
change events to use a single context
removed extraneous is_valid check
removed type specific initializers
check that finalize did not create a new ref
don't zero out refcount in pn_finalize
added assert for null event context; fixed pn_collector_pop to decref context prior to adding event back to the free list
added PN_{CONNECTION,SESSION,LINK}_FINAL events
removed unneeded helper function
made pn_collector_put take the context as an argument
changed EventImpl to use a single context
simplified event posting interface
added INIT events for endpoints