Block path

Blocks can be created in various locations:

• bdsim/blocks holds the standard block set
• roboticstoolbox/blocks holds robot-specific blocks
• machinevisiontoolbox/blocks holds machine-vision specific blocks

Other blocks are looked for along the path given by the environment variable BDSIMPATH which is a colon-separated list of folders.

Within a folder all pythons files, excluding those whose name starts with test_, are parsed for blocks. Each block must have the @block decorator