versioning: Add versioning information: .version, .revision-hash, $ZSH_HIGHLIGHT_VERSION.

* danielsh/versionstamp:
  versionstamp: Set up '.revision-hash' file.
  versionstamp: Handle NO_FUNCTION_ARGZERO.
  Set the version number.

.gitattributes

@@ -0,0 +1 @@
+.revision-hash export-subst

.revision-hash

@@ -0,0 +1 @@
+$Format:%H$

.version

@@ -0,0 +1 @@
+0.3.0-dev

zsh-syntax-highlighting.zsh

@@ -29,6 +29,17 @@
 # -------------------------------------------------------------------------------------------------
 
 
+if [[ -o function_argzero ]]; then
+  # $0 is reliable
+  ZSH_HIGHLIGHT_VERSION=$(<"$0:h"/.version)
+else
+  # $0 is unreliable, so the call to _zsh_highlight_load_highlighters will fail.
+  # TODO: If 'zmodload zsh/parameter' is available, ${funcsourcetrace[1]%:*} might serve as a substitute?
+  # TODO: also check POSIX_ARGZERO, but not it's not available in older zsh
+  echo "zsh-syntax-highlighting: error: not compatible with FUNCTION_ARGZERO" >&2
+  return 1
+fi
+
 # -------------------------------------------------------------------------------------------------
 # Core highlighting update system
 # -------------------------------------------------------------------------------------------------