v0.3.2

Benchmarks against other parsers. No library code changed, and every input
parses to what it did in 0.3.1.

Added

• tools/bench_others.sh: dateparsa against other date parsers on one
  machine. In Zig, against zeit. In Rust, through the C interface, against
  chrono, jiff, time, speedate and dateparser, with heap allocations per
  parse counted. In Python, through the package, against fromisoformat,
  strptime, ciso8601, dateutil, dateparser and pandas, one value at a time
  and down a column. Every parser's answer is checked before it is timed,
  and each harness pins the versions it compares against. docs/PERF.md
  has the first run and what it shows, including what the shared library
  imports: on macOS, bzero, memcpy and memset, and nothing that could
  ask the system for memory.