change suggested func in 'did you mean to use' warning

[ChrisMuir]

Updated the suggested function names passed as args to listwarning(). Here's an example:

stringdist::stringdist(list(55, 56), c(67, 56))

Output is this:

[1] 2 0
Warning message:
In stringdist::stringdist(list(55, 56), c(67, 56)) : 
You are passing one or more arguments of type 'list' to
'stringdist'. These arguments will be converted with 'as.character'
which is likeley not to give what you want (did you mean to use 'seqdist'?).
This warning can be avoided by explicitly converting the argument(s).

seqdist() is not an exported function, but seq_dist() is. This PR changes the suggested function to be seq_dist (same with stringdistmatrix(), the suggested function name passed to listwarning() was edited to be seq_distmatrix).

[coveralls]

Coverage remained the same at 90.438% when pulling 7a49711 on ChrisMuir:master into f530d7f on markvanderloo:master.

[markvanderloo]

Thanks!