- Fixed sympy deprecation warning when using sympy 1.7 and bumped cellmlmanip recuirement up to ensure sympy 1.7 compatibility
- Improved support for secondary trigonometric functions such as sec and acoth.
- When used with Cellmlmanip version 0.2.2+ an improved printing of devisions is used. For example `1 / (1/cos(x))` now gets rendered as `cos(x)` whereas previously it would be `1 / 1 / cos(x)` giving the incorrect result. An side effcet of the change is that powers of formulas get extra brackets e.g. `pow((1 / x), 2)`.
- chaste_codegen uses placeholder functions for some common maths functions like exp, in order to delay evaluation till the point where the code is written. For programmers using chaste_codegen as a library, there now is a function called `subs_math_func_placeholders` which can be used on any sympy expression to substitute these placeholders.
E.g.
>> expr
2.0 * exp_(V)
>> subs_math_func_placeholders(expr)
2.0 * exp(V)