lib: ostream: Allow switching to a specific ioloop.

lib: Add o_stream_get_last_write_time()

lib: Add o_stream_set_finish_also_parent() and _finish_via_child() These allow controlling on both directions whether o_stream_finish() should be finishing the parent stream. If either one is set to FALSE, the parent stream isn't finished. Which one of these to use depends on the situation.

lib: Add o_stream_flush_parent()

lib: Add o_stream_finish() This marks the ostream as fully finished, with no further writes coming to it. Otherwise it behaves like o_stream_flush(). The ostream.flush() methods are supposed to write their trailer (if the ostream has one) when they see that ostream.finished is set. These will be implemented by the following commits.

global: unsigned int:1 -> bool:1 perl -i -pe 's/unsigned int ([^,:;]+):1;/bool $1:1;/' **/*.[ch]

o_stream_send_istream() API changed again The new API enforces the caller to correctly handle all the possible situations. It also makes in unambiguous whether to wait for input or output stream.

lib: Simplified and clarified o_stream_send_istream() API

lib: Don't silently ignore partial writes for o_stream_nsend() Normally o_stream_nsend() should be used only for blocking streams or streams with infinite (or "enough") buffer space.

lib: io_stream_copy() no longer attempts to read full block sizes from input. Although that may be more efficient for writing (to files), it causes unnecessary work for the input stream. The writing part should also be optimized anyway if the caller corks the output stream.

lib: Added o_stream_flush_parent_if_needed() for wrapper ostreams.

ostream: Don't mark the stream closed too early after all. Use another flag instead to avoid losing the last data written to the stream before closing.

Added o_stream_get_fd().

Added o_stream_nsend*() and related functions to make delayed error handling safer. Once o_stream_nsend*() is called, o_stream_nfinish() must be called before stream is destroyed to finish checking if there were any errors. If something failed and the stream is just wanted to be closed, o_stream_ignore_last_errors() can be called. For streams where errors don't really make any difference (network sockets) you can call o_stream_set_no_error_handling() immediately after creating the stream.

Marked functions parameters that are allowed to be NULL. Some APIs were also changed. The non-obvious APIs where NULL parameter was changed to "" are master_service_init() and auth_master_user_list_init(). These checks can currently be enabled only on a patched clang: http://llvm.org/bugs/show_bug.cgi?id=6786

Simplified creating filter ostreams.

Renamed lib/*-internal.h files to lib/*-private.h for consistency.