renderer DrawLine methods with box characters merging

[gdt050579]

Add support in renderer to automatically merge (add special characters) for lines that are crossed over (e.g. ├ , ┼ , ┬ , ┴, ╦ , ╡, ╫, and so on ....). This type of crossed characters should be managed by the framework (e.g. if a draw a vertical line that croses another horizontal line, one of these characters should be automatically added).