update to 2.08 and changes for node v12

[timotejroiko]

Hello, i made some changes a while ago, now i finally had some time to make this PR. Im currently using these changes in production and so far it seems to be working, however it would be good if someone can confirm these changes are properly implemented since im not proficient in C++ and there are some things i was unable to fix.

changes:

• Updated swiss ephemeris to 2.08
• changed several functions to remove deprecation warnings in node v12
• disabled callback function for now (fails to build on node v12, see error below)

todo:

• change callback function to work with Nan::Callback instead. Currently it crashes in v12 with the following error if un-commented in callback.cc (not sure how to properly implement this)

  //fails to build in node v12
  callback.cc: In function ‘void HandleCallback(Nan::NAN_METHOD_ARGS_TYPE, v8::Local<v8::Value>)’:
  callback.cc:9:64: error: no matching function for call to ‘v8::Function::Call(v8::Local<v8::Object>, int, v8::Local<v8::Value> [1])’
  callback->Call (Nan::GetCurrentContext ()->Global (), 1, argv);

• fix deprecation warnings in util.cc (not sure how to properly fix this)

  //sample warning
  util.cc: In function ‘Nan::NAN_METHOD_RETURN_TYPE node_swe_cotrans(Nan::NAN_METHOD_ARGS_TYPE)’:
  util.cc:179:100: warning: ‘v8::Local<v8::Value> v8::Object::Get(uint32_t)’ is deprecated: Use maybe version [-Wdeprecated-declarations]
  xpo [0] = info [0]->ToObject (Nan::GetCurrentContext()).FromMaybe(v8::Local<v8::Object>())->Get (0)->NumberValue (Nan::GetCurrentContext()).ToChecked();

• fix deprecation warnings in hel.cc (not sure how to properly fix this)

  //sample warning
  hel.cc: In function ‘Nan::NAN_METHOD_RETURN_TYPE node_swe_heliacal_ut(Nan::NAN_METHOD_ARGS_TYPE)’:
  hel.cc:43:101: warning: ‘v8::Local<v8::Value> v8::Object::Get(uint32_t)’ is deprecated: Use maybe version [-Wdeprecated-declarations]
  dgeo [0] = info [1]->ToObject (Nan::GetCurrentContext()).FromMaybe(v8::Local<v8::Object>())->Get (0)->NumberValue (Nan::GetCurrentContext()).ToChecked();

im not sure how to go about fixing the remaining issues above without causing problems, so it would be great if someone could help.

[keel]

Thanks for your work! especially the warnings I can not fix. but I'm not sure all this changes are perfectly right, so maybe @mivion should take a look.

[mivion]

Thanks for work. Tests are passed for node v8.0 and 10.0. Should we add v12.0 for test? So I merge this request. If some thing wrong, please make new PR.