Ignore *.hi and *.o files
Merge branch 'next'
Removed Units from Symmath

They were too much alpha for any use
Some more Assoc functions
Showing exponential terms as e^(...) instead of exp(...)
UPN parser added.

Example:

    "a 3 * 4 + arsinh eu x ^ +"

is parsed as

    arsinh((a * 3.0 + 4.0)) + e^(x)

or, in native syntax:

    (Sum (Trigo Arsinh (Sum (Product (Variable 'a') (Number 3.0)) (Number
    4.0))) (Exp (Variable 'x')))
Two more Ln/Log simplify rules.
Parser for sgn, log, ln
Merge branches 'pu/parse' and 'pu/simplify'

UPN parser -> master
Added UPNParse to Symmath module
Introduced root to terms.

Root <base> <exp> is immediately `simplify`ed to <base>^(1/<exp>)
Marked old parser as deprecated
Merge branch 'pu/parse'

Fetching Root from pu/parse
Preventing Prelude.head pattern matching error.
Merge branch 'pu/parse'
Eval clause for roots
UPN tests added
Now using native Show instance for terms.

Traditional show instance renamed as `showTerm :: SymTerm -> String`
Fallback clause in showTerm
Travis CI configuration added