Add initial project files and styles for data visualization

- Created a new Excel file: `departements-francais.xlsx` for data storage.
- Added a CSS file: `style.css` with custom styles for various mathematical environments including boxes for lemmas, theorems, definitions, and more, complete with automatic numbering.
- Initialized R project file: `tp2.Rproj` with default settings for workspace management and LaTeX integration.

M2/Data Visualisation/tp2/tp2.Rproj

@@ -0,0 +1,17 @@
+Version: 1.0
+
+RestoreWorkspace: Default
+SaveWorkspace: Default
+AlwaysSaveHistory: Default
+
+EnableCodeIndexing: Yes
+UseSpacesForTab: Yes
+NumSpacesForTab: 2
+Encoding: UTF-8
+
+RnwWeave: Sweave
+LaTeX: pdfLaTeX
+
+BuildType: Website
+
+SpellingDictionary: fr_FR