Load Custom theme named THEME from its file.
The theme file is named THEME-theme.el, in one of the directories
specified by `custom-theme-load-path'.
If the theme is not considered safe by `custom-safe-themes',
prompt the user for confirmation before loading it. But if
optional arg NO-CONFIRM is non-nil, load the theme without
prompting.
Normally, this function also enables THEME. If optional arg
NO-ENABLE is non-nil, load the theme but don't enable it, unless
the theme was already enabled.
This function is normally called through Customize when setting
`custom-enabled-themes'. If used directly in your init file, it
should be called with a non-nil NO-CONFIRM argument, or after
`custom-safe-themes' has been loaded.
Return t if THEME was successfully loaded, nil otherwise.