Panic fix

• Returning an error in case a number or variable is on the left of a unary operator instead of panicking.
• Fixed benchmarking string in Readme.

Moved itertool dependency to dev

• Moved itertools dependency to dev-dependencies
• Saved a few allocations during parsing
• Fixed benchmarking

Better compile

• breaking public interface - the function pointers of binary operators are now called apply instead of op.
• improved compilation of literals
• removed unnecessary clones during parsing

Fixed doc link

v0.7.1

forgot to safe 😕

Faster parse, Bugfix on multi-unary

• Parsing is now significantly faster, added lazy_static as dependency.
• Fixed that cases with multiple unary operators of an expression containing a binary operator could go wrong.
• Variables do not need to be inside curly brackets anymore.

Even faster evaulation

• Speed up due to
  • flattened expression without any tree or recursive structure
  • more efficient evaluation algorithm without unecessary remove-operations
• Removed possibility to create expressions directly without parsing from public interface

Faster evaluation

• Evaluation is now faster due to

  • fixed repeated prioritization
  • using SmallVec, and
  • compiling expressions.

• The introduction of SmallVec lead to a change in the public interface. In case one wants to create an expression directly without Exmex' parsing functionality one has to use SmallVec or the type defintions exmex::UnaryOpVec or exmex::BinOpVec, see https://docs.rs/exmex/0.5.0/exmex/struct.Expression.html.

Apache 2.0 as new license option

• Added Apache license 2.0 as second option
• Fixed some documentation issues
• More tests