Add test data for recently-added spec changes.

[tgregg]

There is a lack of coverage in the following areas:

• Importing shared symbol tables:
  • Attempting to import a shared symbol table without an exact match.
  • Shared symbol table imports with undefined max IDs.
• Equivalence of symbols with unknown text ($0 and SIDs from a not-found imports).
• The empty symbol appearing in all possible contexts.
• Decimal equivalence:
  • Decimals with overpadded exponents and/or coefficients (binary).
  • Exponent of 0 is equivalent to the same coefficient with an exponent of -0.
  • Normalization of text decimal representations that result in equality under the data model.
• Handling of +inf and -inf without whitespace within s-expressions.
• Invalid cases involving text numbers containing underscores:
  • Numbers with multiple consecutive underscores.
  • Numbers ending in an underscore.
  • Numbers with an underscore in the radix prefix (e.g. 0_xff).
  • Numbers with an underscore immediately following the radix prefix (e.g. 0x_ff).
  • Numbers with an underscore immediately following a minus-sign.
  • Floats/decimals with an underscore immediately preceding or following the exponent character (e.g. 1.0e_2 or 1.0_e2)
  • Floats/decimals with an underscore immediately preceding or following the decimal point.
  • Floats/decimals with an underscore in the exponent.
• Notable non-leap-years, e.g. 1900 and 2100.
• Float equivalence: equivalent 32-bit and 64-bit binary floats.

This issue should be edited as more gaps are found or filled.

[tgregg]

#22 adds coverage for presence of the DEL (0x7F) character in clobs.

[tgregg]

#35 adds coverage for LST append.
#33 and #34 add NOP padding coverage.
#30 adds coverage for floats with underscores.
#31 adds coverage for symbol zero.

Removing those from the list.