Rewrite note parsing in C

This eliminates any parsing choppyness

Fixes: #32
Signed-off-by: William Casarin <jb55@jb55.com>

damus-c/damus.h

@@ -0,0 +1,44 @@
+//
+//  damus.h
+//  damus
+//
+//  Created by William Casarin on 2022-10-17.
+//
+
+#ifndef damus_h
+#define damus_h
+
+#include <stdio.h>
+
+#define MAX_BLOCKS 1024
+
+enum block_type {
+    BLOCK_HASHTAG = 1,
+    BLOCK_TEXT = 2,
+    BLOCK_MENTION = 3,
+    BLOCK_URL = 4,
+};
+
+typedef struct str_block {
+    const char *start;
+    const char *end;
+} str_block_t;
+
+typedef struct block {
+    enum block_type type;
+    union {
+        struct str_block str;
+        int mention;
+    } block;
+} block_t;
+
+typedef struct blocks {
+    int num_blocks;
+    struct block *blocks;
+} blocks_t;
+
+void blocks_init(struct blocks *blocks);
+void blocks_free(struct blocks *blocks);
+int damus_parse_content(struct blocks *blocks, const char *content);
+
+#endif /* damus_h */