Add missing native imports and remove "duplicates"

Currently, ImGui.NET is very close to having full coverage of all cimgui exports for version 1.49. I did a quick diff and identified the following list of functions that are not yet imported. There are also a few functions in ImGuiNative that define helper overloads which call the actual imported function. IMO, there should only be a single import for each cimgui function, and helper overloads should go into the ImGui class, which is supposed to have the safe, friendly wrappers.

@dpethes Did you mention that you were working on TreeNode stuff? I think I am going to try to finish all of the below before I start handling the 1.50 upgrade and breaking changes.

Missing imports (Added in 93f9e60dafe179ec1c584f369db32b522ec5f674)

• igCreateContext
• igDestroyContext
• igGetColorU32
• igGetColorU32Vec
• igGetCurrentContext
• igGetFontTexUvWhitePixel
• igGetKeyIndex
• igGetTreeNodeToLabelSpacing
• igIsItemClicked
• igIsRootWindowOrAnyChildHovered
• igNewLine
• igPlotHistogram2
• igPlotLines2
• igProgressBar
• igSetCurrentContext
• igSetItemAllowOverlap
• igSetNextWindowSizeConstraints
• igTreeAdvanceToLabelPos
• igValueColor
• igValueColor2
• ImFontConfig_DefaultConstructor
• ImGuiIO_ClearInputCharacters

Use va_list or … (problematic)

• igBulletTextV
• igLabelTextV
• igSetTooltipV
• igTextColoredV
• igTextDisabledV
• igTextV
• igTextWrappedV
• igTreeNodePtrV
• igTreeNodeStrV
• igTreeNodeExV
• igTreeNodeExPtr
• igTreeNodeExStr
• igTreeNodeExVPtr

I think we should ignore the above. You can just use string.Format() and pass that to the single-string overload.

Duplicate imports

• ImFontAtlas_AddFontDefault
• igSliderFloat
• igBeginPopupModal (x2)

[mellinoe]

I added the missing imports in 93f9e60dafe179ec1c584f369db32b522ec5f674, and published version 0.2.0 onto NuGet.

[mellinoe]

We have complete coverage in the current version we are targeting (1.50), although there are some new functions and breaking changes in 1.51.