message: fix Term documentation
  u64-based fields are actually 4+8=12 bytes long
diff: @@ -22,10 +22,10 @@ impl Term {
  /// Builds a term given a field, and a i64-value
  ///
  /// Assuming the term has a field id of 1, and a i64 value of 3234,
  - /// the Term will have 8 bytes.
  + /// the Term will have 12 bytes.
  ///
  /// The first four byte are dedicated to storing the field id as a u64.
  - /// The 4 following bytes are encoding the u64 value.
  + /// The 8 following bytes are encoding the u64 value.
  pub fn from_field_i64(field: Field, val: i64) -> Term {
  let val_u64: u64 = common::i64_to_u64(val);
  Term::from_field_u64(field, val_u64)
  @@ -33,11 +33,11 @@ impl Term {
  /// Builds a term given a field, and a f64-value
  ///
  - /// Assuming the term has a field id of 1, and a u64 value of 3234,
  - /// the Term will have 8 bytes. <= this is wrong
  + /// Assuming the term has a field id of 1, and a f64 value of 1.5,
  + /// the Term will have 12 bytes.
  ///
  /// The first four byte are dedicated to storing the field id as a u64.
  - /// The 4 following bytes are encoding the u64 value.
  + /// The 8 following bytes are encoding the f64 as a u64 value.
  pub fn from_field_f64(field: Field, val: f64) -> Term {
  let val_u64: u64 = common::f64_to_u64(val);
  Term::from_field_u64(field, val_u64)
  @@ -46,10 +46,10 @@ impl Term {
  /// Builds a term given a field, and a DateTime value
  ///
  /// Assuming the term has a field id of 1, and a timestamp i64 value of 3234,
  - /// the Term will have 8 bytes.
  + /// the Term will have 12 bytes.
  ///
  /// The first four byte are dedicated to storing the field id as a u64.
  - /// The 4 following bytes are encoding the DateTime as i64 timestamp value.
  + /// The 8 following bytes are encoding the DateTime as i64 timestamp value.
  pub fn from_field_date(field: Field, val: &DateTime) -> Term {
  let val_timestamp = val.timestamp();
  Term::from_field_i64(field, val_timestamp)
  @@ -82,10 +82,10 @@ impl Term {
  /// Builds a term given a field, and a u64-value
  ///
  /// Assuming the term has a field id of 1, and a u64 value of 3234,
  - /// the Term will have 8 bytes.
  + /// the Term will have 12 bytes.
  ///
  /// The first four byte are dedicated to storing the field id as a u64.
  - /// The 4 following bytes are encoding the u64 value.
  + /// The 8 following bytes are encoding the u64 value.
  pub fn from_field_u64(field: Field, val: u64) -> Term {
  let mut term = Term(vec![0u8; INT_TERM_LEN]);
  term.set_field(field);
  @@ -182,7 +182,7 @@ where
  ///
  /// # Panics
  /// ... or returns an invalid value
  - /// if the term is not a `i64` field.
  + /// if the term is not a `f64` field.
  pub fn get_f64(&self) -> f64 {
  common::u64_to_f64(BigEndian::read_u64(&self.0.as_ref()[4..]))
  }
  