We're going to delay NS prefix stripping for a bit. Change the API
dump script accordingly, and bump the Swift name lookup table format
version number so this doesn't break everyone who has already run
swift-api-dump.py.
- Since this file has a Python shebang (`#!/usr/bin/env python`) at the top, it can be invoked directly, without specifying which Python interpreter to use on the command line.
- Use the `%(prog)s` substitution instead of writing the program name again explicitly.
The omit-needless-words script has grown into a more general "API
dumping" script. Make it a bit more useful by installing it alongside
swift-ide-test, symlinking it in the build directory next to
swift-ide-test (for Swift developers), and defaulting to using the
swift-ide-test in the same directory as the script. Now it's fairly
easy to dump the API for a given SDK with, e.g.,
swift-api-dump.py -s iphoneos
