Release 0.8.11 "Accomplishment" - Towards full equation library

This release contains a number of fixes and features intended for use in the equation library being contributed by Jean Wilson

Features

• Accept library items for functionc calls. For example, the expression 'ⓁSiDensity(273_K)' is now accepted. This function is usd in semi-conductor equations in the library.
• The Root command now attempts symbolic solving using the Isol command. This can lead to exact solutions for common equations.
• The SigDig command is a DB48x extension that returns the number of significant digits in a number, i.e. the number of non-zero digits.
• The xpon and mant now apply to unit objects
• Functions now accept assignments as input, e.g. x=9 sqrt gives 3.0
• The equation referenced to by the Equation variable can now be identified using a name.
• The NxEq command now works with quoted equations

Bug fixes

• The ln(1E-100) expression no longer gives a Argument outside domain error. The error was caused by rounding during argument reduction.
• Comparison between a value and a unit object now work correclty
• Arithmetic now correctly deals with dimensionless unit objects, for example in expression '1-1000_mm/m', and improves the evaluation of unit expressions when adding or subtracting unit objects.
• Names containing programs or functions are now evaluated as part of algebraic evaluation
• The solver now correctly processes equations wrapped in an expression.
• Convert now correclty evaluates its arguments when necessary
• Assignment objects no longer cause a crash on error. For example, x='ln(0)' no longer crashes.

Improvements

• Improve solver heuristic when slope is small. This allows the solver to find a solution for an equation like 'tan(x)=224' in degrees mode.
• Add more recorder entries in the solver describing what is being solved.
• Move recorder entries for tests to tests data logger.
• Tests use a larger text rendering limit
• Tests now purge the directory between examples. This prevents stray variables from influencing later tests.
• The handling of long UTF-8 sequences in tests was improved, which allows tests involving a lot of text (e.g. examples) to run faster.