* Add some new expression functions and macros.
See misc/math-expr.md for the list of added functions, except for
"like", which previously existed but was not documented.
* Add easymock to datasketches tests.
* Add easymock to distinctcount tests.
* Add easymock to virtual-columns tests.
* Code review comments.
* Clean up code a bit.
* Add easymock to scan-query tests.
* Rework ExprMacros that have multiple impls.
* Improve test coverage.
* Expressions: Add ExprMacros, which have the same syntax as functions, but
can convert themselves to any kind of Expr at parse-time.
ExprMacroTable is an extension point for adding new ExprMacros. Anything
that might need to parse expressions needs an ExprMacroTable, which can
be injected through Guice.
* Address code review comments.
* Support string type in math expression
addressed comments
addressed comments
Addressed comments
* Updated math function document
* Addressed comments
Gian Merlino
Navis Ryu
Himanshu Gupta