Request: add a createShader( String [] vertSrc, String [] fragSrc ) function like p5.js has

Created by: scudly

Now that we have multi-line strings, it is practical to include shader code directly in sketches (or even to construct them programmatically) rather than reading from an external file. The current publicly supported and documented loadShader() API only cleanly supports reading shaders from files. Ideally, we would also have a createShader( String[] fragSrc ) that infers the type and provides a vertex shader as the current loadShader() does.

Passing the source as an array of strings seems more general than taking it as a single, multi-line string and is trivial enough to express in code. It also matches the existing PShader constructors.

首先检查文档化的 loadShader() API 和现有的 PShader 构造函数，这两者都在 issue 中提到。比较它们对着色器源以及 vertex shader 默认值的处理方式。当 sketch 能够从 String[] 源构造着色器，同时支持显式的 vertex/fragment 形式和请求中描述的推断形式时，工作就完成了。