Add FUNC_WARN_UNUSED_RESULT macro to mark functions whose result should not be ignored
cfengine_stdlib.cf: add a "reached" class like "always" and a scoped generic classes body
Merge pull request #462 from tzz/tzz/generic-classes-2

cfengine_stdlib.cf: add a "reached" class like "always" and a scoped generic classes body.
Pre-release version bump.
Post-release version bump.
Rename IntRange2Int -> IntegerRangeFromString, push out FatalError, PromiseRef
Push FatalError out of Str2Mode
Remove FatalError in HavePublicKey, replace with CfOut
Replace FatalError in dbm filename construction with ProgrammingError
Remove FatalError from Cf3ParseFile, replace with CfOut
Remove FatalError from ConstraintNew, add PromiseCheckType

This improves error output but defers checking of common constraints
attached to promises to eval-time, rather than FatalError'ing out of the
parser. Although the impact should be low, this checking needs to be
brought back at post-parse time (PromiseCheckPartial) soon.
Replace FatalError in ReadDir with ProgrammingError
Fix CfReadLine semantics in error cases
Properly handle errors arising during CfReadLine
Remove documentation for retired features