Fix a WotC-specific bug causing the PCS icon to always be shown on soldiers after researching the breakthrough tech that allows PCS to be reused.

-Add WotC support: Adjust placement of icons so they aren't hidden by the bond icon.
- Fix crash on start of final mission

* Show the upgradable weapon mod icon if a fully-modded weapon has a mod that can be replaced by an improved version of the same type of mod.

* Bugfix for graphical glitch that can sometimes occur when first entering Squad Select. Thanks to LeaderEnemyBoss for discovering this issue.

Updated for attempted compatibility with mods that override UISquadSelect, e.g. the LWS Toolbox and Leader Pack mods. May or may not work with other mods that override this class. Tested to work correctly wtih the Leader Pack and Toolbox with larger squad sizes in two rows.

Note there is a known issue with the Leader Pack: Upgrade icons will not appear after clicking the "Autofill Squad" button. This is a limitation in how autofilling works that I can't easily work around. The icons will appear if you enter and leave a sub-screen (e.g. loadout) after auto-filling.