Plus42 Equations, Preview Release

[Thomas Okken]

New update:

1. The previous update broke the ∫ element, due to the PGMINT → EQNINT split. The generated code used PGMINT, but because it uses an equation object for the integrand, now it needs to use EQNINT.
2. Added sections for list and equation variables to the CATALOG, and also added a section for named equations, i.e. equations that have names in the equation editor. (Equation variables are like any other variable, created with STO and retrieved with RCL; named equations are created in the equation editor, and can be retrieved with GETEQN.) The new sections are in the new OTHER submenu, together with MEM.
3. Exposed the full CATALOG in the equation editor.