Clarification on missing values

[JohnHadish]

This presents two connected issues.

First, there is inconsistency in how the user inputs "NA" data:

For import-emx it is:

--nan <value>
Value Type: String
Default Value: NA
Expected token for expressions that have no value.

For cond-test it is:

--missing <value>
Value Type: String
Default Value: NA
The string that specifies the missing value in the annotation matrix (e.g. NA,
0, 0.0).

It is unclear on if this was intentional since these arguements are dealing with two seperate file types. This can be ignored if so.

The second related issue is that it is unclear in the documentation if the user should designate string missing values as:

--missing NA

OR

--missing "NA"

Online documentation appears to prefer quotes, while documentation shipped with kinc appears to prefer no quotes.

[spficklin]

This was unintentional. I think we can make this fix for the 3.4.2 release to unify them.

[spficklin]

I think for backwards compatibility we should keep both but only document the --nan argument.

[spficklin]

Fixed with merged PR.