Feat87/funcplotter

@Wissam-Halimi  I've modified a couple of things. This version:
- Includes the translation of the tool description
- Solves a minor bug (a single quote was missing at the end of the alert message)
@Wissam-Halimi  I was keeping the capitalization style used originally in the tool. We could use capital letter in all the sentences except for the last one (the one regarding the syntax_error). It's concatenated with the previous sentence.