Print keybindings starting with space correctly

[MaxGyver83]

Bug fix for #1060.

[rnpnr]

Hi Max, thanks for the patch!

This fixes one of the issues listed in #1060 but doesn't replace any additional spaces with ␣. Are you able to address that as well? Maybe a local 18 char buffer to copy key into while replacing with ␣,

[MaxGyver83]

Hi Randy, sure. I didn't think about this.

I have updated this pull request. I hope it's not too complicated. The main difficulty is that spaces (1 byte each) get replaced with ␣ which is 3 bytes but only 1 character. I have limited the number of space replacements to 3 because otherwise the destination string might grow in an unpredictable way.

[rnpnr]

Definitely a little more complicated then I was expecting but its
partially because I forgot how to count bytes. It's on the right track
though so I'll leave some comments inline.

[rnpnr]

Besides the minor comment above this looks good to me. If you want to
squash the commits I would be OK with merging.

I will just wait a couple days to see if anyone else has any comments.

[rnpnr]

Applied! Thanks for your work getting this patch in shape!

[erf]

I get the following warning when building the latest version with this change:

In file included from sam.c:1813:
./vis-cmds.c:663:34: warning: field width should have type 'int', but argument has type 'unsigned long' [-Wformat]
        return text_appendf(data, "  %-*s\t%s\n", 18+invisiblebytes, buf, (char*)value);
                                     ~~~^         ~~~~~~~~~~~~~~~~~
./vis-cmds.c:673:34: warning: field width should have type 'int', but argument has type 'unsigned long' [-Wformat]
        return text_appendf(data, "  %-*s\t%s\n", 18+invisiblebytes, buf, desc ? desc : "");

[MaxGyver83]

I get the following warning when building the latest version with this change:

In file included from sam.c:1813:
./vis-cmds.c:663:34: warning: field width should have type 'int', but argument has type 'unsigned long' [-Wformat]
        return text_appendf(data, "  %-*s\t%s\n", 18+invisiblebytes, buf, (char*)value);
                                     ~~~^         ~~~~~~~~~~~~~~~~~
./vis-cmds.c:673:34: warning: field width should have type 'int', but argument has type 'unsigned long' [-Wformat]
        return text_appendf(data, "  %-*s\t%s\n", 18+invisiblebytes, buf, desc ? desc : "");

Oh, looks like I missed this. I'll change the type of invisiblebytes to int!

[rnpnr]

Fixed in 599ced0. Sorry about that I don't know how I missed it.