Improvements to the calculator.

[Wycklife]

Fixes #5623
This fixes the first 5 parts of the issue.
@africanmathsinitiative/developers This can be reviewed

[Wycklife]

@rdstern I have fixed number 1-5. I need more clarification on number 6 and 7 kindly.

[rdstern]

Hi @Wycklife
I reply first on the changes you have done to items 1 to 5. Then later to clarify 6 and 7.

1. Make the dialogue a bit wider for this keyboard.
2. Add the "stringr::" to the new keys as shown in item 3 in the list. I assume it is needed?
3. Did you do item 4? I couldn't see the pattern = argument in those keys?

[Wycklife]

@rdstern Thanks for the reply, I did item 4. but I can as well have a check on them.

[rdstern]

Here is an indication of the complete keyboard(s) with the items 6 and 7:
(Not quite like this of course - I hope the other keyboards won't go so far down in the dialogue. But I hope the picture explains what could be useful. And this relates also to your proposed presentation in the Zambia meeting.

[Wycklife]

@rdstern I have implemented the two keyboards. Could you kindly check whether the parameters passed by the keys are correct. I have changed the location of the base so as to allow full display of the string keyboard but I have realized it affects other keyboards i'e creating more space. I will ask @dannyparsons to help me solve the problem once he's done with the session.

[Wycklife]

@rdstern I'm happy to make changes you'll suggest.

[Wycklife]

@africanmathsinitiative/developers This is now ready for review.

[rdstern]

@Wycklife this is looking good. So just small suggestions.
a) The group box for Modifiers has an extra line that can be deleted (Compare with the others, Strings or Symbols where there is no extra line.)
b) The symbols keys would ideally be of similar size (as far as possible) so they line up vertically.
c) In the symbol keys you have sometimes added brackets - first 2 rows - and I am not sure they are needed. Can you try without. Then I assume the \ s symbol will have \s space where there wasn't room for \ s (space)?
d) In \ d and \ s there should be no space between \ and s - or \ and d.
e) In the [ ] and [^ ] leave the cursor within the brackets - after the ^. It is now after the brackets.
f) In the {n} and {m,n} keys the key should deliver { } and { , }, i.e. without the n or m and with the cursor just after the first bracket.
g) On the bottom row the + 0 or 1 key should just deliver the + and the same for the other 2 keys.

[Wycklife]

@rdstern I have made the changes. Kindly have a look.

[maxwellfundi]

@rdstern this seems to have been fixed from your comments above.

Cheers.