Some minor fixes to standard library

stdlib/lang/bolt.bolt

@@ -1,10 +1,13 @@
 
+import "../option"
+import "../numbers"
+
 mod Bolt::Lang {
 
   pub struct Pos {
-    offset: Int,
-    line: Int,
-    column: Int,
+    offset: usize,
+    line: usize,
+    column: usize,
   }
 
   pub struct Span {

stdlib/lib.bolt

@@ -0,0 +1,8 @@
+
+pub import "./option"
+pub import "./either"
+pub import "./string"
+pub import "./math.bolt"
+pub import "./vec.bolt"
+pub import "./lang/bolt"
+

stdlib/math.bolt

@@ -1,29 +1,4 @@
 
-pub struct i32;
-pub struct i64;
-pub struct isize;
-pub struct u32;
-pub struct u64;
-pub struct usize;
-
-trait Num;
-
-fn (a: N) + (b: N) -> N where N: Num {
-  N::add(a, b)
-}
-
-fn (a: N) - (b: N) -> N where N: Num {
-  N::sub(a, b)
-}
-
-fn (a: N) / (b: N) -> N where N: Num {
-  N::div(a, b)
-}
-
-fn (a: N) * (b: N) -> N where N: Num {
-  N::mul(a, b)
-}
-
 // precedence a + b < a * b;
 
 pub fn fac(n: I) -> I where I: int {

stdlib/numbers.bolt

@@ -0,0 +1,26 @@
+
+pub struct i32;
+pub struct i64;
+pub struct isize;
+pub struct u32;
+pub struct u64;
+pub struct usize;
+
+trait Num;
+
+fn (a: N) + (b: N) -> N where N: Num {
+  N::add(a, b)
+}
+
+fn (a: N) - (b: N) -> N where N: Num {
+  N::sub(a, b)
+}
+
+fn (a: N) / (b: N) -> N where N: Num {
+  N::div(a, b)
+}
+
+fn (a: N) * (b: N) -> N where N: Num {
+  N::mul(a, b)
+}
+

stdlib/option.bolt

@@ -1,4 +1,3 @@
 
 pub struct Option<T>;
 
-

stdlib/vec.bolt

@@ -0,0 +1,3 @@
+
+pub struct Vec<T>;
+