Demo: Tweaked custom rendering custom, added a Thickness drag. Clarified use of vertical/horizontal line. Add a single pixel demo (wowow)

ColorEdit: Fixed not being able to pass the ImGuiColorEditFlags_NoAlpha or ImGuiColorEditFlags_HDR flags to SetColorEditOptions(). Demo tweak.

Added ImAtof, ImCeil, ImFloorStd to IMGUI_DISABLE_MATH_FUNCTIONS for consistency. Configuration comments.

Added IMGUI_DISABLE_MATH_FUNCTIONS in imconfig.h to make it slightly easier to redefine wrappers to std maths functions such as fabsf(), fmodf(), etc. Comments.

Data types: DragScalar: Fixed speed of integer values tweaking with keyboard/gamepad when speed < 1. Enforce min/max bounds when power curves are used. SliderScalar: Fixed integer/slow tweaking. (#643)

# Conflicts:
#	CHANGELOG.txt
#	imgui.cpp

Scrolling: Fixed a case where using SetScrollHere(1.0f) at the bottom of a window on the same frame the window height has been growing would have the scroll clamped using the previous height. (#1804)

Internals: Made ContentsRegionRect absolute to reduce confusion. Renamed InnerRect to InnerMainRect, renamed WindowRectClipper to OuterRectClipped.

Internals: Nav: Extracted code into a NavClampToVisibleAreaForMoveDir() + fix debug code + inline some functions, removed obsolete EndChild() comment.

Data types: Fix format srtings with leading blanks. Fix ColorEdit4() to not use obsolete formats (when using IMGUI_DISABLE_OBSOLETE_FUNCTIONS) (#643)

Apply fix from data_types branch, some widgets broken when format string doesn't contains a %. Broken by 92f0165f. Data_types branch fix c5fb9295.

Internals: Declaring DragBehavior, SliderBehavior in there (no warantee given) as they may be useful to custom widgets.

Moved DragScalar, InputScalar, SliderScalar to imgui.h as well as ImGuiDataType (#320, #643, #708, #1011)

Fix to allow compiling in unity builds where stb_rectpack/stb_truetype may be already included in the same compilation unit.

Settings: Added LoadIniSettingsFromDisk(), LoadIniSettingsFromMemory(), SaveIniSettingsToDisk(), SaveIniSettingsToMemory(), io.WantSaveIniSettings. (#923, #993)

Internals: Removed unnecessary allocation indirection for g.LogClipboard (this only made sense when there was a global context instance)

Skip missing font glyphs to 1) avoid using space for missing glyphs and 2) allow merging fonts with overlapping ranges. Demo: Fixed displaying ? instead of greyed out empty box.  (#1671, #1703)

add backuping transform for Dx9 impl
(#1790, #1687)

SliderScalar, VSliderScalar(): Support for any data types. Tested with various ranges/limits. Note that Drag/Slider/Input currently fail if the format string doesn't preview the actual value. Will fix next. (#320, #643, #708, #1011)

Internals: A few selected math helpers are now using template to handle all supported types. Added ImPow() to wrap float/double in a standard manner without calling pow(double) when not needed in Drag code.

Internals: Data types: Made format string optional. DragBehavior: Moved a bit of code outside of the template. Slider tidying up. Removed unnecessary call to fabsf().

DragFloat, DragInt: Default format string is none is passed to the function. Fixed demo using old style %.0f.