Add non-ascii check to code policy
Remove non-ascii chars from source
Fix non-ascii chars in API testcase

Merge two test cases in the process.
Merge branch 'code-policy-nonascii'
Ditz issue update
add knownissue
Merge branch 'fix-tonumber-roundtrip-test'
Bug testcase for duk_peval_file() nonexistent file
Fix duk_peval_file() & co nonexistent file bug

duk_push_string_file_raw() can be made to push undefined for a file read
error; after that, compile will throw a "no sourcecode" error.  This is
not an ideal error messages but good enough for now.
Release note: duk_peval_file() fix
Authors: add credit
Merge branch 'fix-peval-nofile'

Fix bug in duk_peval_file(), duk_peval_file_noresult(), and duk_peval_compile()
where a non-existent file would cause the functions to throw.  This is
obviously unexpected because the API calls are supposed to be protected.
With this fix they now return rc=1 and the error on the stack will be
"Error: no sourcecode" (not ideal, but works for now).
Ditz issue update
Makefile size output, dump-public symbols
Dump leaked duk__ symbols in dump-public
Add DUK_SINGLE_FILE to single file duktape.h

This is needed by symbol visibility macros.
Missing static declarations
First draft of symbol visibility macros

For GCC 4+ these now produce a nice clean build when compiling the split
compiler source files.  Without these, the result is quite messy.
Some internal documentation on symbol visibility
Code issues section heading trivia