64-bit fixes
64-bit fixes

`int` values are not the same thing as `size_t` nor `ptrdiff_t`. Convert incorrect uses of `int` to more appropriate types.

Fixes warnings for 64-bit compilations.
nProtect/imgui,ocornut/imgui,tom-seddon/imgui,gyakoo/imgui,zho7611/imgui,rmoorman/imgui,wangshijin/imgui,rxantos/imgui,cmaughan/imgui,tpoechtrager/imgui,ggtucker/imgui,Flix01/imgui,Psybrus/imgui,Pagghiu/imgui,redblobgames/imgui,emoon/imgui,benoitjacquier/imgui,xythobuz/imgui,benoitjacquier/imgui,rmoorman/imgui,wflohry/imgui-addons,ghassanpl/imgui,rxantos/imgui,luiseduardohdbackup/imgui,cmaughan/imgui,sakishum/imgui,Flix01/imgui,cmaughan/imgui,mikesart/imgui,wangshijin/imgui,ghassanpl/imgui,wasikuss/imgui,seanmiddleditch/imgui,xunmengfeng/imgui,aimotive/imgui-glfw,wflohry/imgui-addons,tpoechtrager/imgui,DXsmiley/FlexGUI,memononen/imgui,neshume/imgui,luiseduardohdbackup/imgui,bagobor/imgui,seanmiddleditch/imgui,bkaradzic/imgui,ocornut/imgui,thennequin/imgui,bkaradzic/imgui,tom-seddon/imgui,cmaughan/imgui,emoon/imgui,DXsmiley/FlexGUI,elect86/imgui,nmlgc/imgui,nProtect/imgui,nmlgc/imgui,usagi/imguixx,adairdavid/imgui,andresv/imgui,adairdavid/imgui,thennequin/imgui,gyakoo/imgui,bagobor/imgui,kylawl/imgui,redblobgames/imgui,thevaber/imgui,nProtect/imgui,xunmengfeng/imgui,shaggytwodope/imgui,dougbinks/imgui,memononen/imgui,xythobuz/imgui,sakishum/imgui,Extrawurst/imgui,GHF/imgui,ggtucker/imgui,andresv/imgui,neshume/imgui,ocornut/imgui,aimotive/imgui-glfw,zho7611/imgui,burningreggae/imgui,kylawl/imgui,mikesart/imgui,shaggytwodope/imgui,wasikuss/imgui,dougbinks/imgui,twigletguy/imgui,bkaradzic/imgui,elect86/imgui,burningreggae/imgui,twigletguy/imgui,thevaber/imgui,usagi/imguixx,Psybrus/imgui,Flix01/imgui,ggtucker/imgui,gamedeff/imgui,Pagghiu/imgui,gamedeff/imgui,Extrawurst/imgui,GHF/imgui