Added 2 void functions for input of text after compile.

[Vadenez]

P.S Im a newbie to C++
Commit 1:
Srry i couldn't figure out the format of cvui.h, so this better work.
I've made an attempt at the idea of text input, this allows me to create a "inputBox" that I can only type in after clicking on it.
ive also create a more basic version that inputs any letters typed, aslong as inputField = true.
It shouldn't let weird characters pass, like ñ and Ȣ.
It also has full functionallity of backspace, but not tab.
only thing is 25% of the time what you input doesn't input, atleast for me 👎 .
https://github.com/Vadenez/cvui

Commit 2:
improved consistance from 25% to bout 50%, and made text slightly change color wether or not allowInput is true or false. Made they strings instead of void, so you can process the input better,
Ex. password validator.
Another problem I've found is that it can't tell the difference between one use of the function and another use of the function, meaning that 2 input boxes with have the same text inside them.

Also if you want to see it in action, im using it for one of my projects (https://github.com/Vadenez/VOLT-Banking). And, I've made a bunch of "random" functions using cvui, that im using in VOLT-Banking these are here: https://github.com/Vadenez/VOLT-Banking/blob/master/Bank/headers/functions.h

[Dovyski]

Thank you for your contribution! I am currently working to update all cvui code base. Your pull request will be merged soon.