[WIP] Rewriting the Univariate Solver

This PR aims to rewrite a cleaner and robust univariate equation solver.
    - [x] polynomial
    - [x] rational
    - [x] trigonometric
    - [ ] functions solvable by LambertW
```
from sympy.utilities.misc import filldedent
print (filldedent('''
    Warning: inequalites with complex variables
    are not supported when solving an inequality'''))
```

And do you just want to print this or did you intend to raise a ValueError?