script: fix uninitialized pointer in detailed view of a script
core: fix compiler warning on freopen (ignore file returned)
core: rename binary and man page from "weechat-curses" to "weechat" (task #11027)

A symbolic link weechat-curses -> weechat is now created (by both cmake and
configure), so that the /upgrade will work from an old version.

However, if you upgrade from an old version, it is recommended to force the use
of the new binary name with the command: `/upgrade /path/to/weechat` (replace
the path accordingly).