Release 0.5.2 "Christmas Eve": Reaching hard limits on the DM42

This release was a bit longer in coming than earlier ones, because we are about
to reach the limits of what can fit on a DM42. This release uses 711228 bytes
out of the 716800 (99.2%).

Without the Intel Decimal Library code, we use only 282980 bytes. This means
that the Intel Decimal Library code uses 60.2% of the total code space. Being
able to move further requires a rather radical rethinking of the project, where
we replace the Intel Decimal Library with size-optimized decimal code.

As a result, release 0.5.2 will be the last one using the Intel Decimal Library,
and is release in parallel with 0.6.0, which switches to a table-free and
variable-precisions implementation of decimal code that uses much less code
space. The two releases should otherwise be functionally identical

New features

• Shift and rotate instructions (#622)
• Add CompatibleTypes and DetsailedTypes setting to control Type results
• Recognize HP-compatible negative values for flags, e.g. -64 SF (#625)
• Add settings to control multiline result and stack display (#634)

Bug fixes

• Truncate to WordSize the small results of binary operations (#624)
• Fix day-of-week shortcut in simulator
• Avoid double-evaluation of immediate commands when there is no help
• Generate an error when selecting base 1 (#628)
• Avoid Number too big error on based nunbers
• Correctly garbage-collect menu entries (#630)
• Select default settings that allow solver to find solutions (#627)
• Fix display of decimal numbers (broken by multi-line display)
• Fix rendering of menu entries for Fix, Std, etc
• Detect non-finite results in arithmetic, e.g. (-8)^0.3m (#635, #639)
• Fix range-checking for Dig to allow -1 value
• Accept large values for Fix, Sci and Eng (for variable precision)
• Restore missing last entry in built-in units menu (#638)
• Accept Hz and non-primary units as input for ConvertToUnitPrefix (#640)
• Fix LEB128 encoding for signed value 64 and similar (#642)
• Do not parse IfThenElse as a command
• Do not consider E as a digit in decimal numbers (#643)
• Do not parse min as a function in units, but as minute (#644)

Improvements

• Add OnesComplement flag for binary operation (not used yet)
• Add ComplexResults (-103) flag (not used yet)
• Accept negative values for B→R (according to WordSize)
• Add documentation for STO and RCL accessing flash storage
• Mention True and False in documentation
• Rename MaxBigNumBits to MaxNumberBits
• Return HP-compatible values from Type function
• Minor optimization of flags implementation
• Catalog auto-completion now suggests all possible spellings (#626)
• Add aliases for CubeRoot and Hypothenuse
• Align based number promotion rules to HP calculators (#629)
• Expand the range of garbage collector integrity check on simulator
• Show command according to preferences in error messages (#633)
• Avoid crash in debug_printf if used before font initialization
• Update performance data in documentation
• Add ability to disable any reference to Intel Decimal Floating-point library
• Simplify C++ notations for safe pointers (+x and operartor bool())
• Fix link to old db48x project in README.md

Full Changelog: v0.5.1...v0.5.2