Added ConvertTo<*> methods in exec.cpp, and eval_<*> methods in express.cpp
Added Eval(Optional)ExprAs<Type>() methods in exec.cpp, where <Type> = BooleanRef, DataRef, etc
[[ RefactorSyntax ]] EP-less implementation of MCChunk::getobj added
[[ RefactorSyntax ]] MCClose::exec updated
[[ RefactorSyntax ]] MCEncryptionOp::exec refactored
[[ refactorSyntax ]] All MCChunk's EP-based functions replaced with EP-less ones
The EP-based methods are now based on an MCExecContext
[[ refactorSyntax ]] MCExport::exec refactored
[[ RefactorSyntax ]] MCChunk's functions using EP reverted
They were wrapping the new EC-based functions, but issues arose
[[ RefactorSyntax ]] MCFilter:exec updated
Merged branches refactor-syntax_unicode_shims

Conflicts:
    engine/src/exec.h
    engine/src/exec.cpp
[[ RefactorSyntax ]] MCImport::exec updated
[[ RefactorSyntax ]] EvalOptionalExprAsStringRef updated to EvalOptionalExprAsNullableStringRef when needed
Merge branch 'refactor-syntax_unicode_shims' into refactor-syntax_unicode_shims1

Conflicts:
	engine/src/exec.cpp
	engine/src/exec.h
[[ RefactorSyntax ]] Fixed typo
[[ RefactorSyntax ]] MCOpen::exec updated
[[ RefactorSyntax ]] Update the changes - Eval... actually returns a bool, which makes checking way faster
Couple of mistakes corrected
Merge branch 'refactor-syntax_unicode_shims' into refactor-syntax_unicode_shims1
[[ RefactorSyntax ]] Change few lines to directly use the return value of EvalExprAs
[[ RefactorSyntax ]] Updated few lines to directly use the return value of getobj()
Merge branch 'refactor-syntax_unicode_shims' into refactor-syntax_unicode_shims1