Fix for correctness and allow non-auto resized modals to have window minimum size applied - hopefully no-side effects (#249)

Minor construction fix (-1.0 is correct "disabled" value for TextWrapPos, didn't have any incidence anyway)

Fixed SetNextWindowPosCenter() being processed too early for windows that are still measuring their size (for #249)

InputTextMultiline() painfully merged most computation passes into one, better clipping, much faster for large text (#200)

InputText: fixed handling of scaled font. re-organized bits of code toward merging all sizes calculations (#200)

InputText(): removed extraneous CalcTextSizeW call for tracking cursor/scrolling, remove spike (#200)