Avoid bash way, improve posix shell portability
Added DSCP support
Refactored DSCP-related code a bit
Add --enable-color option to enable/disable terminal color output
Minor DSCP-related improvements

- Improved usage annotation
- Shifted DSCP value to set not whole DS field, but only it's DSCP part
Implement new RPC authorization using --rpc-secret option
Add future deprecation warning to --rpc-user and --rpc-passwd
Improved dscp parameter description
Merge branch 'dscp-support' of https://github.com/iavael/aria2 into iavael-dscp-support

Conflicts:
	src/prefs.cc
	src/prefs.h
	src/usage_text.h
Fix longer line in --dscp option help
Document --dscp option in manual page
Better handling of 30X HTTP status codes

Reference: http://greenbytes.de/tech/tc/httpredirects/
Treat 30X response without Location header field as error

This is required to make segmented download work.
Update doc
Add numStoppedTotal key to aria2.getGlobalStat() RPC method response

It shows the number of stopped downloads in the current session and
not capped by --max-download-result option. On the other hand, the
existing numStopped key also shows the number of stopped downloads,
but it is capped by --max-download-result option.
Update aria2c.rst
Add some missing includes to AnnounceList.h
Warn if neither --rpc-secret nor a combination of --rpc-user/rpc-passwd is set
Don't allow empty string for --rpc-secret option
Add aria2.saveSession RPC method

This method saves the current session to a file specified by
--save-session option. This method returns "OK" if it succeeds.