Internals: Added support for overriding locale decimal point, undocumented. (#2278) + Misc doc update.

Doc: Mention IMGUI_VERSION_NUM in recent api breaking changes + textwrap some demo code.

imgui.cpp

@@ -380,6 +380,7 @@ CODE
                        - if you set the 'power' parameter to >1.0f (to enable non-linear editing): 1/ your compiler may warn on float>int conversion, 2/ code will assert at runtime, 3/ in case asserts are disabled, the code will not crash and enable the _Logarithmic flag. 4/ you can replace the >1.0f value with ImGuiSliderFlags_Logarithmic to fix the warning/assert and get a _similar_ effect as previous uses of power >1.0f.
                        see https://github.com/ocornut/imgui/issues/3361 for all details.
                        kept inline redirection functions (will obsolete) apart for: DragFloatRange2(), VSliderFloat(), VSliderScalar(). For those three the 'float power=1.0f' version were removed directly as they were most unlikely ever used.
+                       for shared code, you can version check at compile-time with `#if IMGUI_VERSION_NUM >= 17704`.
                      - obsoleted use of v_min > v_max in DragInt, DragFloat, DragScalar to lock edits (introduced in 1.73, was not demoed nor documented very), will be replaced by a more generic ReadOnly feature. You may use the ImGuiSliderFlags_ReadOnly internal flag in the meantime.
  - 2020/06/23 (1.77) - removed BeginPopupContextWindow(const char*, int mouse_button, bool also_over_items) in favor of BeginPopupContextWindow(const char*, ImGuiPopupFlags flags) with ImGuiPopupFlags_NoOverItems.
  - 2020/06/15 (1.77) - renamed OpenPopupOnItemClick() to OpenPopupContextItem(). Kept inline redirection function (will obsolete).