Feat comparisons and numbers

[PEXEL2002]

Description

This PR introduces critical parser improvements requested by the instructor and resolves priority issues with stacked fractions.

1. Floating-Point Numbers (Dot & Comma)

• Updated the NUMBER token in the Lexer to accept both dot (3.14) and comma (3,14) formats.
• Added a conversion in the Visitor: every comma in a numeric value is automatically replaced with a dot in the resulting LaTeX output to maintain mathematical consistency.

2. Multi-Variable Functions

• Implemented the argumentList rule, allowing functions with any number of arguments (e.g., f(x, y), g(a, b, c)).
• Added a COMMA token as an argument separator.
• Note: For multi-variable functions, it is recommended to use a space after the comma to avoid ambiguity with the Polish decimal format.

3. Fraction Priority Fix (//)

• Refactored the hierarchy in the expression rule. Division (fractions) now has a higher priority than implicit multiplication.
• Behavior Examples:
  • Input 1 // 2 x now correctly generates \frac{1}{2} x (previously x was pulled into the denominator).
  • Input 1 // {2x} (or with grouping) correctly generates \frac{1}{2x}.

4. Enhanced Comparison Operators

• Implemented a robust set of comparison operators with support for multiple notations (ASCII, Unicode, and keywords):
  • Less than or equal: <= or ≤
  • Greater than or equal: >= or ≥
  • Not equal: !=, <>, or ≠
  • Equality: =, ==, or the keyword rowne
  • Basic relations: < and >
• Rule Logic: Implemented a specific logic where inequalities require both sides, while the equality operator (=) allows for an empty right-hand side (to support "step-by-step" math solving).

Test Cases

Input (Natural Math)	LaTeX Output	Notes
x rowne 5	x = 5	Keyword equality
a != b	a \neq b	LaTeX command mapping
2,5 + 3.5	2.5 + 3.5	Unified to dot format
f(a, b, c)	f(a, b, c)	Multi-variable support
1 // 2 x	\frac{1}{2} x	Correct priority
1 //{2x}	\frac{1}{2x}