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/symbol.src

@@ -55,44 +55,44 @@
 χ	chi
 °	deg	degree
 δ	delta
-Δ	De
+Δ	De	Delta
 ↓	dn	down
 ₑ	_e
 ε	eps
 η	eta
 凸	fuck
 γ	gamma
-Γ	Ga
+Γ	Ga	Gamma
 ⁱ	^i
 ∫	II	integral
 ∞	inf	infinity
 ι	iota
 κ	kappa
 λ	lambda
-Λ	La
+Λ	La	Lambda
 ×	mul	times
 μ	mu
 ⁿ	^n
 ν	nu
 ω	omega
-Ω	Om
+Ω	Om	Omega
 ●	oo	circle
 ₒ	_o
 φ	phi
-Φ	Ph
+Φ	Ph	Phi
 π	pi
 Π	Pi
 ∏	PP	prod
 ψ	psi
-Ψ	Ps
+Ψ	Ps	Psi
 ρ	rho
 σ	sigma
-Σ	Si
+Σ	Si	Sigma
 √	sq	sqrt
 ∑	SS	sum
 τ	tau
 θ	theta
-Θ	Th
+Θ	Th	Theta
 ↑	up
 υ	ups
 ✓	vv	check