Add random dangerosity level

[ptitmorceaux]

This pull request introduces a new mechanism for determining the dangerosity level of monster encounters and updates the configuration of creature groups to better reflect different dangerosity levels. The main changes include the addition of a function to randomly select dangerosity levels for encounters, updates to how dangerosity is set in the game logic, and improvements to the configuration file for creature groups.

Gameplay logic improvements:

• Added a new function getRandomDangerosityLevel() that selects a dangerosity level based on weighted probabilities (1: 40%, 2: 30%, 3: 20%, 4: 10%) (creatures.c, creatures.h). [1] [2]
• Updated the monster zone logic to use getRandomDangerosityLevel() instead of a fixed value, making encounters more dynamic (jeu.c).
• Clarified that boss zones always use dangerosity level 5 in the code (jeu.c).

Configuration updates:

• Revised groupes.conf to uncomment and adjust groups for dangerosity levels 1, 4, and 5, providing more accurate and varied group definitions for each level (groupes.conf). [1] [2]