vendor: update all dependencies

* Update all dependencies
  * Remove all `[[constraint]]` from Gopkg.toml
  * Add in the minimum number of `[[override]]` to build
  * Remove go get of github.com/inconshreveable/mousetrap as it is vendored
  * Update docs with new policy on constraints

vendor/google.golang.org/api/sheets/v4/sheets-gen.go

@@ -941,6 +941,11 @@ func (s *BasicChartDomain) MarshalJSON() ([]byte, error) {
 // one for the "Open Price", "High Price", "Low Price" and "Close
 // Price".
 type BasicChartSeries struct {
+	// Color: The color for elements (i.e. bars, lines, points) associated
+	// with this
+	// series.  If empty, a default color will be used.
+	Color *Color `json:"color,omitempty"`
+
 	// LineStyle: The line style of this series. Valid only if the
 	// chartType is AREA,
 	// LINE, or SCATTER.
@@ -1004,7 +1009,7 @@ type BasicChartSeries struct {
 	// chart</a>.
 	Type string `json:"type,omitempty"`
 
-	// ForceSendFields is a list of field names (e.g. "LineStyle") to
+	// ForceSendFields is a list of field names (e.g. "Color") to
 	// unconditionally include in API requests. By default, fields with
 	// empty values are omitted from API requests. However, any non-pointer,
 	// non-interface field appearing in ForceSendFields will be sent to the
@@ -1012,8 +1017,8 @@ type BasicChartSeries struct {
 	// used to include empty fields in Patch requests.
 	ForceSendFields []string `json:"-"`
 
-	// NullFields is a list of field names (e.g. "LineStyle") to include in
-	// API requests with the JSON null value. By default, fields with empty
+	// NullFields is a list of field names (e.g. "Color") to include in API
+	// requests with the JSON null value. By default, fields with empty
 	// values are omitted from API requests. However, any field with an
 	// empty value appearing in NullFields will be sent to the server as
 	// null. It is an error if a field in this list has a non-empty value.
@@ -2075,7 +2080,7 @@ type BooleanCondition struct {
 	// Supported by data validation.
 	// Requires a single ConditionValue,
 	// and the value must be a valid range in A1 notation.
-	//   "ONE_OF_LIST" - The cell's value must in the list of condition
+	//   "ONE_OF_LIST" - The cell's value must be in the list of condition
 	// values.
 	// Supported by data validation.
 	// Supports any number of condition values,
@@ -2778,8 +2783,9 @@ type ChartSourceRange struct {
 	// The domain (if it exists) & all series must have the same number
 	// of source ranges. If using more than one source range, then the
 	// source
-	// range at a given offset must be contiguous across the domain and
-	// series.
+	// range at a given offset must be in order and contiguous across the
+	// domain
+	// and series.
 	//
 	// For example, these are valid configurations:
 	//
@@ -3221,7 +3227,7 @@ type ConditionValue struct {
 
 	// UserEnteredValue: A value the condition is based on.
 	// The value will be parsed as if the user typed into a cell.
-	// Formulas are supported (and must begin with an `=`).
+	// Formulas are supported (and must begin with an `=` or a '+').
 	UserEnteredValue string `json:"userEnteredValue,omitempty"`
 
 	// ForceSendFields is a list of field names (e.g. "RelativeDate") to
@@ -5313,20 +5319,21 @@ func (s *HistogramChartSpec) UnmarshalJSON(data []byte) error {
 //     | Grand Total |            $29.12 |
 //     +-------------+-------------------+
 type HistogramRule struct {
-	// End: Optional. The maximum value at which items will be placed into
-	// buckets
+	// End: The maximum value at which items will be placed into buckets
 	// of constant size. Values above end will be lumped into a single
 	// bucket.
+	// This field is optional.
 	End float64 `json:"end,omitempty"`
 
-	// Interval: Required. The size of the buckets that will be created.
-	// Must be positive.
+	// Interval: The size of the buckets that will be created. Must be
+	// positive.
 	Interval float64 `json:"interval,omitempty"`
 
-	// Start: Optional. The minimum value at which items will be placed into
+	// Start: The minimum value at which items will be placed into
 	// buckets
 	// of constant size. Values below start will be lumped into a single
 	// bucket.
+	// This field is optional.
 	Start float64 `json:"start,omitempty"`
 
 	// ForceSendFields is a list of field names (e.g. "End") to
@@ -8967,11 +8974,11 @@ type WaterfallChartCustomSubtotal struct {
 	// indices,
 	// but subtotals do not affect the indices of the data points.
 	// For
-	// example, if a series has 3 data points, their indices will always be
-	// 0,
-	// 1, and 2, regardless of how many subtotals exist on the series or
-	// what
-	// data points they are associated with.
+	// example, if a series has three data points, their indices will
+	// always
+	// be 0, 1, and 2, regardless of how many subtotals exist on the series
+	// or
+	// what data points they are associated with.
 	SubtotalIndex int64 `json:"subtotalIndex,omitempty"`
 
 	// ForceSendFields is a list of field names (e.g. "DataIsSubtotal") to