Use UTF-8 for diagnostic output if it is available. Added a command line

switch --no-utf8 to disable the use of UTF-8 characters.

doc/ca65.sgml

@@ -120,6 +120,7 @@ Long options:
   --listing name                Create a listing file if assembly was ok
   --list-bytes n                Maximum number of bytes per listing line
   --memory-model model          Set the memory model
+  --no-utf8                     Disable use of UTF-8 in diagnostics
   --pagelength n                Set the page length for the listing
   --relax-checks                Relax some checks (see docs)
   --smart                       Enable smart mode
@@ -147,7 +148,7 @@ Here is a description of all the command line options:
   name="search paths">.
 
 
-  <label id="option-color">
+  <label id="option--color">
   <tag><tt>--color</tt></tag>
 
   This option controls if the assembler will use colors when printing
@@ -262,6 +263,14 @@ Here is a description of all the command line options:
   huge.
 
 
+  <label id="option--no-utf8">
+  <tag><tt>--no-utf8</tt></tag>
+
+  Disable the use of UTF-8 characters in diagnostics. This might be necessary
+  if auto detection fails or if the output is captured for processing with a
+  tool that is not UTF-8 capable.
+
+
   <label id="option-o">
   <tag><tt>-o name</tt></tag>