release: 0.2.7

Version bump plus a doc sweep: the benchmark tables in README and
docs/OPTIMIZATIONS.md were still from before the typed calling convention,
OPTIMIZATIONS listed BEGIN loop promotion as not started, and the
subroutine-threading section of docs/WAFER.md described the memory ABI as
the only one.

Cargo.lock

@@ -1589,7 +1589,7 @@ checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
 
 [[package]]
 name = "wafer"
-version = "0.2.6"
+version = "0.2.7"
 dependencies = [
  "anyhow",
  "clap",
@@ -1600,7 +1600,7 @@ dependencies = [
 
 [[package]]
 name = "wafer-core"
-version = "0.2.6"
+version = "0.2.7"
 dependencies = [
  "anyhow",
  "insta",
@@ -1615,7 +1615,7 @@ dependencies = [
 
 [[package]]
 name = "wafer-web"
-version = "0.2.6"
+version = "0.2.7"
 dependencies = [
  "anyhow",
  "js-sys",