Buy similar: combine same stats from different mods

[vaisest]

Description of the problem being solved:

Fixes trade search for repeated mods with the same stats. For example breath of aldur weapons or items with resistances transformed to chaos res.

to # mods now also use the midpoint for the search.

Steps taken to verify a working solution:

• Tested with various items from the trade site

Link to a build that showcases this PR:

https://pobb.in/xLtX_75reIyy

Before screenshot:

The resulting trade search was also wrong as it only takes into account the first filter for each stat.

After screenshot:

[vaisest]

While taking screenshots I noticed the fields floor float values and didn't accept floats. This seems a bit misleading for e.g. flat crit so in the last commit I made mod fields float valued. Many mods use integer values, but even if the user inputs a float, it shouldn't affect anything since the trade site seems to floor them (though don't quote me on that)