build, data: the Greek capitals by name; one way to run python3; bench.sh checks its own binary

Δ Γ Λ Ω Φ Ψ Σ Θ answered only to De, Ga, La, Om, Ph, Ps, Si, Th, while
their small letters answered to delta, gamma and the rest; they answer to
the names too now.  mkemoji and cldr2emoji write UTF-8 whatever the
locale, as the other generators already did; verify-map calls python3 the
one way; the tests' include path drops a directory nothing includes
through; and bench.sh says which binary is missing instead of blaming the
daemon ten seconds later.

map/cldr2emoji

@@ -28,6 +28,8 @@ def annotations(path):
 
 
 def main():
+    sys.stdout.reconfigure(encoding="utf-8")
+    sys.stderr.reconfigure(encoding="utf-8")
     if len(sys.argv) < 3:
         print(f"usage: {sys.argv[0]} emoji-test.txt annotations.json...",
               file=sys.stderr)