cppcheck static code analysis reveals some true positives

[plugins/trailfocus/src/trailfocus.cpp:227]: (style) Unused variable: iter

[plugins/thumbnail/src/thumbnail.cpp:284]: (style) Variable 'distance' is assigned a value that is never used.

[plugins/td/src/3d.cpp:491] -> [plugins/td/src/3d.cpp:495]: (performance) Variable 'rv' is reassigned a value before the old one has been used.

[src/screen.cpp:2700]: (performance) Prefix ++/-- operators should be preferred for non-primitive types. Pre-increment/decrement can be more efficient than post-increment/decrement. Post-increment/decrement usually involves keeping a copy of the previous value around and adds a little extra code.

[src/window.cpp:3449]: (performance) Prefix ++/-- operators should be preferred for non-primitive types. Pre-increment/decrement can be more efficient than post-increment/decrement. Post-increment/decrement usually involves keeping a copy of the previous value around and adds a little extra code.
[src/window.cpp:3459]: (performance) Prefix ++/-- operators should be preferred for non-primitive types. Pre-increment/decrement can be more efficient than post-increment/decrement. Post-increment/decrement usually involves keeping a copy of the previous value around and adds a little extra code.
[src/window.cpp:4062]: (performance) Prefix ++/-- operators should be preferred for non-primitive types. Pre-increment/decrement can be more efficient than post-increment/decrement. Post-increment/decrement usually involves keeping a copy of the previous value around and adds a little extra code.

[plugins/decor/src/decor.cpp:890]: (error) Uninitialized variable: frameType
[plugins/decor/src/decor.cpp:891]: (error) Uninitialized variable: frameState
[plugins/decor/src/decor.cpp:892]: (error) Uninitialized variable: frameActions

[plugins/group/src/glow.cpp:323] -> [plugins/group/src/glow.cpp:346]: (performance) Variable 'x2' is reassigned a value before the old one has been used.

[plugins/resize/src/logic/src/resize-logic.cpp:1372] -> [plugins/resize/src/logic/src/resize-logic.cpp:1379]: (performance) Variable 'lco' is reassigned a value before the old one has been used.
[plugins/resize/src/logic/src/resize-logic.cpp:1372] -> [plugins/resize/src/logic/src/resize-logic.cpp:1380]: (performance) Variable 'rco' is reassigned a value before the old one has been used.
[plugins/resize/src/logic/src/resize-logic.cpp:1372] -> [plugins/resize/src/logic/src/resize-logic.cpp:1381]: (performance) Variable 'tco' is reassigned a value before the old one has been used.
[plugins/resize/src/logic/src/resize-logic.cpp:1372] -> [plugins/resize/src/logic/src/resize-logic.cpp:1382]: (performance) Variable 'bco' is reassigned a value before the old one has been used.

[plugins/resizeinfo/src/resizeinfo.cpp:138]: (warning) %d in format string (no. 1) requires a signed integer given in the argument list.
[plugins/resizeinfo/src/resizeinfo.cpp:138]: (warning) %d in format string (no. 2) requires a signed integer given in the argument list.