Use local variables for Ragel.

Instead of using instance variables for ts, te, etc we'll use local variables.
Grand wizard overloard @whitequark suggested that this would be quite a bit
faster, which turns out to be true. For example, the big XML lexer benchmark
would, prior to this commit, complete in about 9 - 9,3 seconds. With this
commit that hovers around 8,5 seconds.
Benchmark for measuring average lexing times.
Dropped the benchmark_ prefixes.

These files reside in a benchmark/ directory. Gee, I wonder what they do.
Cleaned up benchmarking code.