Updating the error message for unbound variables. Fixing issue #684.
Removing an extra space.
Updating the error message and removing the special case for the java backend.
Fixing some of the hidden warnings found in /include directory (typing all variables, singleton variables become anonymous, . is .K)
Merge pull request #692 from kframework/fixHiddenWarnings

Fixing some of the hidden warnings found in /include directory
Fixing one of the tests.
Merge pull request #685 from kframework/fixFreshError

Updating the error message for unbound variables. Fixing issue #684.
Merge branch 'unified-builtins2' into fixVarTypeInference2
Trying to infer the most concrete empty element that fits in the context.
   - modified the type filter to prefer terms of sort directly subsorted to the context, and discard K if it can
   - pushed instantiation of middle end classes for list terminator after parser in order to have a more uniform representation for disambiguation.