Feature Request: More `less`-like key bindings

[jqnatividad]

As csvlens is patterned after less, some other less key bindings to consider:

• Home, End keys to go to top/bottom of CSV respectively
• ^RightArrow - Right to last column
• ^LeftArrow - Left to first column
• h key for Help Screen showing key bindings

[arildm]

• d Down half a page
• u Up half a page
• h Show help page with key bindings

[YS-L]

Thanks for the suggestions! These are now added in v0.4.0.