windows compilation issue when building huge msg

[muratory]

when using custom message with big structure, we may reach the windows compilator limit of 65535 character for a string.

This happens in msg creation when building the comment string in escape_message_definition function.

proposed patch is to break when 64000 size limit is reached 👍
def escape_message_definition(definition):
lines = definition.splitlines()
if not lines:
lines.append('')
s = StringIO()
count = 0
for line in lines:
line = _escape_string(line)
# individual string literals cannot be too long; need to utilize string concatenation for long strings
# https://docs.microsoft.com/en-us/cpp/c-language/maximum-string-length?view=vs-2017
s.write('"%s\n"\n' % (line))
#patch to exit when line total greater than 64000 due to windows compil limitation
count = count + len(line) + 6
if count > 64000:
break
val = s.getvalue()
s.close()
return val

[dirk-thomas]

Please consider to create a pull request with your proposed patch.