Refit mode

[lbmaian]

Implement refit mode using calculation described at https://forums.sufficientvelocity.com/threads/starfleet-ship-design-bureau-to-boldly-go.33039/page-184#post-9274965

• [x] Dropdown allowing selection of another saved ship design to refit from
• [x] Calculate refit costs in addition to the standard calculations
• [x] Determine how refit costs will be displayed (including in summary)
• [x] Optional: comparison mode (diff stats/costs rather than construct refit costs) - would require a comparison/refit toggle

[lbmaian]

Refit cost formula:

if part name is the same:
    if new cost >= old cost:
        new cost - old cost
    else:
        (new cost - old cost) / 2
else:
    new cost - old cost / 2

Important note: "part name" needs to also include phaser arrays and burst torps if applicable, since those virtually each double the number of phaser/torp parts.

[lbmaian]

Important note: "part name" needs to also include phaser arrays and burst torps if applicable, since those virtually each double the number of phaser/torp parts.

With #63 and #71, this is no longer necessary.

[lbmaian]

Refit and compare design modes have been implemented and deployed. Any bugs with the implementation will be addressed separately.

[lbmaian]

With #63 and #71, this is no longer necessary.

Even though this is the case, since the toggles still exist for the time being (and in case any future toggles might exist), adding code to treat phaser arrays and burst torp toggles as part of the "part name" when determining refit costs.