Line comments instead of block comments 2

Continuation of #138.

As I was viewing the code, I noticed certain types of comments that I may not be supposed to edit, so I chose to omit them. These comments can be categorized into four groups:

Comments with /*!***/: They seem to have a special type of formatting, which is consistent with some C files I came across that were not created by Norm. Specifically, I looked at mmfatl.c by @wlammen and mmtest.c by @digama0, both of which have comments already updated in the // form, except for the /*!***/ ones, so they seem to be intentionally built this way.

Comments that have multiple ***: It appears that they are intended to be noticeable, for example like the header that is present at the beginning of every file:

/*****************************************************************************/
/*        Copyright (C) 2018  NORMAN MEGILL                                  */
/*            License terms:  GNU General Public License                     */
/*****************************************************************************/
/*34567890123456 (79-character line to adjust editor window) 2345678901234567*/

Or like the following comment:

 /*** See the comments in mmvstr.h for an explanation of these functions ******/

So I left those out too (the header has the same formatting in the already updated mmfatl.c mmtest.c files too).

Comments that are inside the code: These are probably the most uncontroversial ones since they wouldn't work with //, unless with some rewrapping of the code itself. Example:
```
 if (graphicsChar == 218 /* up left */ || graphicsChar == 217 /* lo r */
      || graphicsChar == 191 /* up r */ || graphicsChar == 192 /* lo l */)
```
Technically the comment /* lo r */ isn't strictly between coding characters, so it could be edited with // lo r, but it's clearly of the same type of the neighbouring ones, so I left it out too.
Multiline commented out C code: It appears that it was intended to be easily uncommented for experimental use. Since line comments would be less practical for this purpose, I left the original block ones. Example:
```
// For debugging
/*
```

int main(void) { vstring_def(s); vstring_def(t);

printf("Hello\n"); let(&t,edit(" x y z ",2)); let(&s,cat(right("abc",2),left("def",len(right("xxx",2))),"ghi",t,NULL)); printf("%s\n",s); printf("num %s\n",num(5)); printf("str %s\n",str(5.02)); printf("num1 %s\n",num1(5.02)); printf("time %s\n",time()); printf("date %s\n",date()); printf("val %f\n",val("6.77")); }

*/ In general my convention knowledge for C is very limited, so I built these criteria by intuition. Let me know if you agree with these criteria or if there are some standards that you are aware of.

metamath / metamath-exe

Line comments instead of block comments 2 #139