Can't encode large integer attributes

`json2geobuf` exits with this error:

```
/usr/local/lib/node_modules/geobuf/node_modules/pbf/index.js:429
throw new Error('Given varint doesn\'t fit into 10 bytes');
```

when given this input (the `overflow` test from Tippecanoe):

```
{"type":"FeatureCollection","features":[
{"type":"Feature","properties":{"excess":2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":22e291},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":2.5},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":2147483648},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":-2147483648},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":2147483647},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":-2147483647},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":18446744073709551616},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":-18446744073709551616},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":18446744073709551615},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":-18446744073709551615},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":9223372036854775808},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":-9223372036854775808},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":9223372036854775807},"geometry":{"type":"Point","coordinates":[0,0]}}
,
{"type":"Feature","properties":{"excess":-9223372036854775807},"geometry":{"type":"Point","coordinates":[0,0]}}
]}
```

Reproduce the failure through json2geobuf using the supplied overflow input, then inspect the varint error in pbf/index.js and compare it with Tippecanoe's overflow test. Trace how large integer attributes are encoded and establish the expected handling for the listed integer and floating-point values; done means the input no longer exits with the 10-byte varint error.

Written by the indexing model from the issue text.