* Fix GetCodepointNext to return default value with size=0 on invalid input. Modify LoadCodepoints to work when GetCodepointNext returns a size of 0. All internal use of GetCodepointNext and GetCodepointPrev checked. This fix may break external code dealing with invalid input as the old code erroneously never returned a size of 0, external code that doesn't properly check for size=0 may endlessly loop or overflow a buffer on invalid input.

* Change default behaviour of GetCodepointNext to return a size of 1 instead of 0. This matches existing prod behaviour and guarantees size 1..4 is returned. Simplify internal code that uses GetCodepointNext that previously had to account for size=0.

* Simplified progressing through a UTF-8 string in ImageTextEx and MeasureTextEx. This change matches existing precedent in DrawTextEx

* GetCodepointNext: Add 10xxxxxx checks to multibyte encodings.

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Co-authored-by: anon <anon>

Basic packing algorithm currently follows this order: Copy pixel data -> Move offsetX for current glyph -> Check remaining space for current glyph...
Since X offset already moved according current glyph, remaining space should be checked for next glyph. Because of this, occasionally, current logic causes glyphs wrapping around texture.
Proposed fix accomplishes that by moving offsetX check to the beginning of the loop.

* Calculate exact image size in GenImageFontAtlas

Calculate exact image size with a method based on total glyph width and glyph row count
Current method seemed a little bit overkill with square root, log and power functions and only approximates image size which can be wonky with some weird fonts like cursive fonts.
Proposed method calculates image size directly with a simpler method and results exact image size needed.

* Update rtext.c

* Update rtext.c

Changed do-while to while loop, and also added an extra step to calculate maximum glyph width and excluding it from image width for extra safety.

* Fixed some grammar mistakes.

* Fixed some typos.

These IsReady() functions provide a method in order to verify whether or not the object was loaded successfully. They're useful to make sure the assets are there prior to using them.

There were a few raylib modules that continued to use TraceLog() instead of the TRACELOG() macro. This change ensures that all the internal raylib modules use the TRACELOG() pattern consistently.

- ADDED: `GetCodepointPrevious()`
 - RENAMED: `GetCodepoint()` -> `GetCodepointNext()`, actually, reimplemented
 - `GetCodepoint()` has been kept for the moment, for compatibility and also because implementation is different
 - RENAMED: `TextCodepointsToUTF8()` to `LoadUTF8()`, simpler name and more aligned with raylib conventions (functions loading memory start with Load*()), parameters should be descriptive of functionailty.
 - ADDED: `UnloadUTF8()`, aligned with `LoadUTF8()` to avoid allocators issues.

This truncation causes text that spans the zero coord boundary to round differently left or zero vs. right of zero, in turn causing letters to appear squished together. If you actually need the position to be an integer, you should instead `floorf()` the float, rather than doing an integer truncation, but I don't see any reason to convert it to an integer in the first place. Everything else in the equation is a float.

Just reviewed font atlas size estimation, now it considers `fontSize` instead of `chars[i].image.height`, increasing considerably the atlas size estimation.

* Add DrawTextCodepoints

* Fixed top comment

Allow to choose which modules are compiled with raylib, if some modules are excluded from compilation, required functionality is not available but smaller builds are possible.

- All variables are initialized on declaration, some arrays were not properly initialized
 - Static array buffers require memset() for re-initialization on every function call

Avoid crash on wrong sprite font

raylib modules have been slightly renamed to add some identity and note that they are independent modules that can be used as standalone separate parts of raylib if required.

The renamed modules are:
 - `core` -> `rcore`
 - `shapes` -> `rshapes`
 - `textures` -> `rtextures`
 - `text` -> `rtext`
 - `models` -> `rmodels`
 - `camera` -> `rcamera`
 - `gestures` -> `rgestures`
 - `core` -> `rcore`

All the build systems has been adapted to this change.