Fix bugs

[ghost]

Hi !

• As i explained in issue Bug in ThemeGeneratorCommand : title_case #40, the method title_case is not available since 5.7.
  I have changed the method to Str::title.

• There is another bug : symlink. I have used another name than "Themes", and i had a message error :

symlink(): File exists

Because, it is missing a little condition in :

if (!File::exists(public_path('Themes')) && config('theme.symlink') && File::exists(config('theme.theme_path'))) {

---> As i used another name, with this condition, it checked if "Themes" exists in public path. In my cas, it doesn't exist but it is already symlink with another name. So, on every boot, this class try to symlink to path which is already exist.

I have added a "&& !File::exists(config('theme.symlink_path'))" in this condition.

• Another bug with other name than "Themes" : getFullPath. This method used the name "Themes" by default if there is a symlink. I fixed it by :

$themePath = str_replace(base_path('public') . DIRECTORY_SEPARATOR, '', $this->config[ 'theme.symlink_path' ]) . DIRECTORY_SEPARATOR.$themeName.DIRECTORY_SEPARATOR;;

• Clean style ci error

It is now worked with my project ( i use Laravel Framework 7.9.2). (Sorry for multiple commits. It is my first time...)

Best regards.

[Shipu]

Thank you so much. and I want to merge your pull request by ignoring your multiple commits