ensure an early death for Jessie/TL2014 systems

also, drop trailing periods from messages; 1.3

unicodedomino.sty

@@ -28,7 +28,7 @@
 % makes all UTF-8 available in listings.
 
 \NeedsTeXFormat{LaTeX2e}%
-\ProvidesPackage{unicodedomino}[2018/08/05 1.3~ Domino for unknown codepoints]%
+\ProvidesPackage{unicodedomino}[2018/08/05 1.3 Domino for unknown codepoints]%
 \makeatletter%
 
 \ifx\numexpr\@undefined%
@@ -37,6 +37,11 @@
 \ifx\UTFviii@defined\@undefined%
  \PackageError{unicodedomino}{This package requires UTF-8 input encoding}%
 \fi%
+\ifx\decode@UTFviii\@undefined%
+ \PackageError{unicodedomino}%
+  {Your utf8.def is too old, consider updating it}%
+  {You will need Debian stretch or newer}%
+\fi%
 
 % patch up bug in utf8.def that forbade 0xF4 lead byte
 \begingroup%
@@ -210,7 +215,7 @@
    \PackageError{inputenc}{%
     Invalid\space UTF-8\space byte\space sequence:%
     \expandafter\unicodedomino@splithex\string#1\relax%
-   }{Do ensure the source document is saved in UTF-8 encoding.}%
+   }{Do ensure the source document is saved in UTF-8 encoding}%
   \fi%
  \else%
   % known char, expand