Bug Fix: 'type' required as domain parameter for WeierstrassCurve, TwistedEdwardCurve and MontgomeryCurve

[greuet]

Hi,

I tried to define a TwistedEdwardCurve by hand, e.g.

from ecpy.curves import TwistedEdwardCurve

p_25519 = 2**255 - 19
a_25519 = -1
d_25519 = 0x52036cee2b6ffe738cc740797779e89800700a4d4141d8ab75eb4dca135978a3
Gx_25519 = 0x216936d3cd6e53fec0a4e231fdd6dc5c692cc7609525a7b2c9562d608f25d51a
Gy_25519 = 0x6666666666666666666666666666666666666666666666666666666666666658
q_25519 = 2**252 + 27742317777372353535851937790883648493

cv = TwistedEdwardCurve ({'name': 'myTECurve',
                          'size': 256,
                          'a': a_25519,
                          'd': d_25519,
                          'field': p_25519,
                          'generator': [Gx_25519, Gy_25519],
                          'order': q_25519})

but I got an error because the 'type' key was expected as a domain parameter.

Then I set 'type' inside the class initialization for WeierstrassCurve, TwistedEdwardCurve and MontgomeryCurve, so that as described in the documentation, it is not needed anymore as a parameter.