ImVector: reserve() tweak to avoid undefined behavior warning (#731)
ImVector: reserve() tweak to avoid undefined behavior warning (#731)

Psybrus/imgui,aimotive/imgui-glfw,ocornut/imgui,bkaradzic/imgui,nProtect/imgui,nProtect/imgui,thevaber/imgui,burningreggae/imgui,dougbinks/imgui,cmaughan/imgui,thennequin/imgui,Pagghiu/imgui,wflohry/imgui-addons,wflohry/imgui-addons,bkaradzic/imgui,burningreggae/imgui,wasikuss/imgui,mikesart/imgui,aimotive/imgui-glfw,cmaughan/imgui,nProtect/imgui,Psybrus/imgui,Pagghiu/imgui,thevaber/imgui,cmaughan/imgui,Flix01/imgui,ocornut/imgui,ggtucker/imgui,elect86/imgui,thennequin/imgui,ggtucker/imgui,Flix01/imgui,cmaughan/imgui,wasikuss/imgui,tom-seddon/imgui,bkaradzic/imgui,tom-seddon/imgui,elect86/imgui,ocornut/imgui,ggtucker/imgui,dougbinks/imgui,seanmiddleditch/imgui,mikesart/imgui,Flix01/imgui,seanmiddleditch/imgui