context: improve message args parsing

[70sh1]

This is achieved by using strings.Fields instead of strings.Split

This results in a cleaner output when parsing messages like /tags a lot of spaces

Output before: []string{"a", "", "", "", "", "", "", "", "", "", "lot", "", "", "", "", "", "", "", "", "of", "", "", "", "", "", "", "", "spaces"}

Output after the change: []string{"a", "lot", "of", "spaces"}