Improve `verify_data` function

[pepijnvink]

Automatically parse allowed data types rather than manual specification. Additional checks if data are of type matrix are left in. Should resolve #85

[hanneoberman]

I believe that a better solution would be https://rlang.r-lib.org/reference/arg_match.html

[hanneoberman]

Maybe using tryCatch could work:

• check if argument input is of type data.frame,
• if not, catch error and check if argument input is of type mids,
• if then not, throw error

https://adv-r.hadley.nz/conditions.html#handling-conditions

[pepijnvink]

Should also resolve #130