Fix several warnings, changed some struct members from char to int

[mingodad]

Nice project ! In this first look I fixed several compiler warnings.

[mingodad]

TODO: need to free wat_strs in function to_wat.c::tree_to_wat

[LingDong-]

Hi @mingodad ,

Thanks so much for all the fixes!

Looks good! Just wondering about a couple things:

• Changing (x)?(y):(z) to x?y:z, wouldn't that become problematic if one of the three operands is an assignment? e.g. (x=0)?1:2 is different from x=0?1:2. Or perhaps not omitting the parenthesis in (x=y) also avoids the problem.
• So glad the segfault is fixed! So it looks like it was because some of the structs are not zeroed? Just curious.
• Changing char struct members to int: I know due to alignment, the final size of the struct won't be affected in those cases, but is there any particular reason for the change?

I haven't tested the changes yet, will clone your fork in a bit and try them out :)

Thanks again for the fixes!