add literal str print in asyncmsg

[zxkmm]

Continue work of #2111
previously:
asyncmsg can only handle string obj. for example

std::string xxx = "xxx";
asyncmsg(xxx);

but not

asyncmsg("xxx");

now:

std::string xxx = "xxx";
asyncmsg(xxx);

and

asyncmsg("xxx");

are both OK

i think all template should keep in header, but to satisfying this change, i have to moved all implementation into source file (to make it readable).

but since both header and source files are fake, so you need to include both of them, when using this class, which is not elegant but i don't have any other better way.

[gullradriel]

Well. I think it would be better to have it in only one header, it will be easier to include without modifying the Makefile
That aside I'm all on for the update.

[zxkmm]

But in standard, the non template methods should be in cpp.
but if you don’t mind the standard I think I can move them together back in header.

[zxkmm]

@gullradriel i edited code per your requests

[gullradriel]

Standard are made to be broken 💔
I would prefer all in a header, as it's going to be easier to use that way.
It's up to you to make a choice ^^

[zxkmm]

Thanks! I will choose your way until I find a better way.