Cleanup errors after LocalOperator merge

See merge request !266

Test more grids in gradient test

See merge request !262

Add correct break condition to operator-list assemble method

See merge request !265

replace explicit child type deduction with global type-traits

See merge request !264

Return vector by reference and typo corrections

See merge request !263

Make the backend solver directly accessible in ProblemStat

See merge request !261

Simplify linear algebra backend LinearSolver

See merge request !260

fix problems after merge

See merge request !259

Test all backends in gitlabci

Closes #16

See merge request !256

Move all recursive algorithms to algorithm subdirectory

See merge request !255

Implement Operator and LocalOperator with TypeErasure

See merge request !204

change version number to 0.3

See merge request !254

simplify ProblemStatTest by just assembling and not solving the linear system

Exptacted GridFunctionOperatorTransposed from GridFunctionOperator

Add enumerate algorithm and remove exclusive_scan

See merge request !252

Correct naming of operator in addOperator() function of LinearForm and BiLinearForm

See merge request !253

Cleanup the treepath functions and concepts

See merge request !251

Allow std containers as coefficients in DiscreteFunction and allow DefaultGlobalBasis

See merge request !248

add unified access for the implementation of DiscreteFunction

Improved test and range initialization of DiscreteFunction

extend the DiscreteFunctionTest to test for construction with std containers

Add range type to solution() and oldSolution() functions