Improved project description.
Made several improvements to subtypes of the plisp_node_t any-type.

- Moved important constants into separate file, to allow for overriding when compiling library for special circumstances.
- Improved documentation.
- String type is now a plain c-string divided into shards. The plans on using a global string table were discarded, for now.
- Symbols are to refer to some position in the evaluator stack during runtime, rather than directly to concrete nodes.
Added scribbles to documentation.

Contains information relevant during development. The information is to be re-written later when the project starts to approach completion.
Added empty implementation of plisp_parse() function.
Added Palm's C Library to project.
Changed structure of plisp_tree_t.

Also cleared function implementations belonging to the type.
Replaced interpreter with evaluator, as the latter name is shorter.