Various bug fixes and small features (#606)

* Fix stray cursor, integer overflows and other bugs

* check for getenvlist error, shorten code

* fix cascade, set info_line before auth, make code clearer and a bug fix

* Add option to turn on numlock at startup

* Fix setting numlock

* Update build.zig

* Custom info text

* Shift+Tab for previous input

* update changelog and res/config

* Some fixes

* update build.zig

* update build.zig again

* Fix xauth command for some shells and fix building in ReleaseSafe

* Use git describe to get dev version str

* revert change to getLockState (it broke the doom animation)

* add new ly error messages. Only try to make path for pam/exe during install when dest_directory is defined + print warning on error.

* add warning message for workaround

changelog.md

@@ -10,6 +10,9 @@ res/config.ini contains all of the available config options and their default va
 + `term_restore_cursor_cmd` should restore the cursor to it's usual state.
 + `vi_mode` to enable vi keybindings.
 + `sleep_key` and `sleep_cmd`.
++ `numlock` to set numlock on startup.
++ `initial_info_text` allows changing the initial text on the info line.
++ `box_title` to display a title at the top of the main box
 
 Note: `sleep_cmd` is unset by default, meaning it's hidden and has no effect. 
 
@@ -45,3 +48,5 @@ session_index = 0
 + Non .desktop files are now ignored in sessions directory.
 + PAM auth is now done in a child process. (Fixes some issues with logging out and back in).
 + When ly receives SIGTERM, the terminal is now cleared and existing child processes are cleaned up.
++ Shift+Tab now focuses previous input.
++ Display text in the info line when authenticating.