Updates to make_phenotypes function

[TolhurstBiometrics]

Potential minor updates:

1. Allow 'error_df' to pass the three error components to the output data frame when return.effects = TRUE

2. Provide flexibility to allow non-numeric factors, particularly for 'env' and 'id'

3. Relax need for 'env' column when gv_df and error_df is just one environment

4. Handle 'gv_df' without the rep column, so that the reps are padded out internally according the number of blocks in 'error_df'. This will also have ramifications on the asr_output wrapper functions, whereby the user will not need to specify 'rep'. Also has ramification for the extensions below, i.e. incomplete block designs.

Alternatively, the 'rep' column is used to allocate rep'd genotypes to blocks in terms of an incomplete block design, so that the 'asr_output' functions are responsible for determining rep'd genotypes based on user-defined inputs of non-integer values.

[TolhurstBiometrics]

Potential major updates:

1. Provide flexibility for incomplete block designs, including p-rep designs

2. Provide flexibility to pass an externally generated design

[TolhurstBiometrics]

The env column is factorising numeric as 1 10 11 ... 2 20 etc Not sure if id has the same issue