Fix type for AnalyticFunction

[patrick330602]

Fix AnalyticFunction type affecting rowNumber, rank and DenseRank.

The problem

I discovered during development, where TypeScript complains:

Argument of type '{ column: string; order: "desc"; }' is not assignable to parameter of type '"oid" | "oid"[] | { columnName: "oid"; order?: "asc" | "desc" | undefined; nulls?: "first" | "last" | undefined; }'.
  Object literal may only specify known properties, and 'column' does not exist in type '"oid"[] | { columnName: "oid"; order?: "asc" | "desc" | undefined; nulls?: "first" | "last" | undefined; }'.

However, they are clearly using column in the code:

knex/lib/query/analytic.js

Lines 21 to 49 in 4c79ac1

	partitionBy(column, direction) {
	assert(
	Array.isArray(column) || typeof column === 'string',
	`The argument to an analytic partitionBy function must be either a string
	or an array of string.`
	);
	if (Array.isArray(column)) {
	this.partitions = this.partitions.concat(column);
	} else {
	this.partitions.push({ column: column, order: direction });
	}
	return this;
	}
	orderBy(column, direction) {
	assert(
	Array.isArray(column) || typeof column === 'string',
	`The argument to an analytic orderBy function must be either a string
	or an array of string.`
	);
	if (Array.isArray(column)) {
	this.order = this.order.concat(column);
	} else {
	this.order.push({ column: column, order: direction });
	}
	return this;
	}

Also, this can verify that using columnName is apparently incorrect:

[coveralls]

Coverage remained the same at 92.27% when pulling 7cc863b on patrick330602:master into 2dadde4 on knex:master.