Add mising functions and add second way to add user function

[MrHIDEn]

Add USER_FUNCTIONS to keep user functions names.
Add second version of adding user function. 'f(x)=2*x'
Add clear functions.
Add clear constants.
Add tests.
Update version.

[gunnarmein-ts]

I like your changes! What do you think we should do about documentation, as Martin owns that?

[MrHIDEn]

Well, dono, I've seen he had version 1.13 on his page. so he perhaps pulled your changes to his repo or what?

• maybe we should ask him
• do we want make own www page? its money.
• we can also add DOC folder (DOC, DOCS, DOCUMENTATION) and write documentation there in markdown files
• we can also place docs on your github if it is not taken yet

https://together-science.github.io/
https://together-science.github.io/nerdamer-prime

[MrHIDEn]

I will add some example to README file which I've forgotten.

[MrHIDEn]

https://jekyllrb.com/ Markdown files to pages -> jekyll build to make html files
https://www.mkdocs.org/ MkDocs
https://vuepress.vuejs.org/ VuePress

[gunnarmein-ts]

Let's continue this discussion in email (rather than in a closed PR): gunnar@together.science.