Fix bug caused by same attribute used in different choice tabs.
Fix bug caused by same attribute used in different choice tabs.

Still need to fix the list of values in these attributes, e.g. "text" node contains form which is used for terms or variables with different values for each case.

refs #101

fbennett/csl-editor,citation-style-editor/csl-editor,citation-style-language/csl-editor,adam3smith/csl-editor,citation-style-editor/csl-editor,citation-style-editor/csl-editor,citation-style-language/csl-editor,adam3smith/csl-editor,adam3smith/csl-editor,citation-style-language/csl-editor,fbennett/csl-editor