Benchmarking with Criterium

[daveyarwood]

Use Criterium to build a range of benchmarks to test the performance of this library's functions vs. their pure Java equivalents.

Examples of things to benchmark:

• Find some large body of text that will likely contain at least some supplementary characters, e.g. a Chinese blog. Break the string of text down into characters using char-seq. Get the code-point-of each character.
• Convert a large number of integers in the range 0 - 1114111 (BMP + Supplementary character ranges) to characters using char'. The current implementation of char' relies on dynamic type inspection to determine if the argument is a character or a string (supplementary characters have to be represented in string form), so it will be interesting to see if this function's performance can be improved (see issue #2 ).
• Benchmark char-range for large ranges of characters in the BMP range, the Supplementary range, and ranges spanning both.

[daveyarwood]

Added benchmarks for char'. The next thing is to add some benchmarks for processing text from websites, with varying amounts of supplementary characters, in order to benchmark char-seq and code-point-of.