fix for freetype glyph loading

Added a preprocessor definition to disable the use of stb_image

Fixed Signed/Unsigned Comparison Warning

In Visual Studio 17, I get warnings related to these variables:
````
fontstash.h(241): warning C4018: '<': signed/unsigned mismatch
fontstash.h(242): warning C4018: '<': signed/unsigned mismatch
````

Making them unsigned fixes it.

Bind a dummy texture in setUniforms when compiling with emscripten

- nvgTextBreakLines: wordMinX was relative to rowStartX, which caused
problems when rowStartX change on line break, but wordMinX was still
relative to the previous rowStartX
- fixed font size on perf graphs
- made demo to use row minx/maxx instead of row->width
- fixed demo hover distance

fixes the WebGL error "RENDER WARNING: there is no texture bound to the unit 0"" in Chrome

Fixes demo’s font sizes.

Fixes the issue that line gap may ruin the text layout.

This commit fixes the demo’s font sizes for the changes in #558, which makes the rendered font size matches what you saw on other native apps. The demo used bigger font sizes than they actually were. This commit deduces the font sizes to match the original demo’s look.

Support for resetting fallback fonts.

This commit adds `nvgResetFallbackFontsId()` and `nvgResetFallbackFonts()` functions for resetting fallback fonts.

Pass fringe parameter to renderTriangles

Support for loading a certain font face from a font file.

This commit allows loading a certain font face from a font collection file such as TTC.

Fixes the issue that font size is inconsistent.

This commit fixes the issue that font size is inconsistent between different font files. `stb_truetype.h` is also updated to the latest version to support additional font types such as OpenType fonts.

Fix fox #542, indicate font licenses

Fix compile issue for missing { in fontstash.h

Fixes memory leaks of freetype.

This commit fixes the issue that freetype library isn’t released in `fonsDeleteInternal()` and causes memory leaks.

Fixes the bug that gl may fail to draw fringes.

This commit fixes the bug that `glnvg__convexFill()` tried to draw fringes depending on whether `NVG_ANTIALIAS` is set. However, #386 adds `nvgShapeAntiAlias()` for chaning anti-alias state explicitly, and `glnvg__convexFill()` would cause error If the anti-alias state is disabled.

Fix example crash on 32bit platform

Update README.md with another project link

Forces autohint when loading glyph using FreeType.

This commit adds the `FT_LOAD_FORCE_AUTOHINT` parameter to `FT_Load_Glyph()` to fix wonky characters.

Fixes text corruption on atlas rebuild.

This commit fixes #494.

Fixes the type of view size.

This commit changes the type of the view size accepted by `nvgRenderFrame()` from `int` to `float` so it matches the type defined in `GLNVGcontext`. This would prevent a framebuffer missing a pixel in final rendering result.

- disable stroke AA gradient when not using AA

Use GLES2 glTex[Sub]Image2D code paths also for GL2

Mark devicePixelRatio unused in glnvg_renderViewport

Resets font atlas when it is full.

This commit updates font stash to render glyph's bitmap data on demand. This change is intended to fix the issue that `nvgTextBounds()` may return an unreliable result when font atlas is full. This situation usually happens when auto scaling a large font text to fit a small rectangle.

The `fons__getGlyph()` function now accepts a new parameter indicating whether bitmap data is optional, and only `nvgText()` requires it. All of `nvgTextGlyphPositions()`, `nvgTextBreakLines()`, `nvgTextBounds()` and `nvgTextBoxBounds()` functions are changed to work without glyph’s bitmap data.