Fix issue 730

[teddychao]

Fixes #730.

Changes proposed in this pull request:

• Update pspm_help to make it able to read help text from source code.
• Update help text for functions.

After testing, almost all the functions can be read, with a few exceptions as following

• pspm_get_timing: Arguments are written in a different method.
• pspm_jobman: The symbol → is not read by pspm_help.
• pspm_load_channel: Arguments are not sorted conventionally.
• pspm_load_data: Arguments are not sorted conventionally.
• pspm_process_illuminance: There are second-level subfields.
• pspm_pupil_pp_options: Arguments are not sorted conventionally.
• pspm_tam: There are second-level subfields.

[teddychao]

It can generate the struct now but have not sorted subfields. Will do next

[teddychao]

Example

[teddychao]

Example 2