Implemented functionality for changing methods

**Notice** that I created a new file under `tests/regression/` called `test-dataMashR.R`. It contains simple tests for 2 of the new functions I implemented. I'm not really sure whether those should be and whether they were run or not. But I believe they should all pass as they did on my machine. Please double check that.

- First pull this new version and reinstall dataMashR, i.e. `make roxygen` and then `make`
- Then, on baad try this

```{coffee}
library(dataMashR)
fullChangeOfMethods(c('m1', 'a', 'd'), paste0('mx', 1:3))
```

- Then do `git status` and `git diff config/methodsDefinitions.csv` to see what changes were made. I think the entire file will change in this first trial as the current `config/methodsDefinitions.csv` does not contain quotes.
- `fullChangeOfMethods` changes all `dataMatchColums.csv` and also `methodsDefinitions.csv`
- make sure to reset this trial change in the end on baad, i.e. `git reset --hard`