Allow for smartcase search

[resolritter]

Vim has the 'smartcase' option which works as follows:

Override the 'ignorecase' option if the search pattern contains upper case characters. Only used when the search pattern is typed and 'ignorecase' option is on.

I use that option in Vim, so I would like to have it in ov as well. It could be implemented as follows:

if config.SmartCaseSearch {
  caseSensitive = searchInput.HasUpperCase()
} else {
  caseSensitive = config.CaseSensitive
}