fix(docs,rpc,u): cleanup fixed8 remnants

[ixje]

Bumped into some fixed8, did a grep and found more leftovers. There's still some stuff in /common/ but it says that is auto-generated.

./common/api/neon-core.api.md:function fixed82num(fixed8hex: string): number;
./common/api/neon-core.api.md:function Fixed8Parser(item: StackItemJson): number;
./common/api/neon-core.api.md:function num2fixed8(num: number, size?: number): string;
./common/api/neon-core.api.md:        Fixed8Parser,
./common/api/neon-core.api.md:        num2fixed8,
./common/api/neon-core.api.md:        fixed82num,
./common/api/neon-core.api.json:              "canonicalReference": "@cityofzion/neon-core!rpc.Fixed8Parser:function(1)",
./common/api/neon-core.api.json:              "docComment": "/**\n * Parses the result to a Fixed8.\n */\n",
./common/api/neon-core.api.json:                  "text": "export declare function Fixed8Parser(item: "
./common/api/neon-core.api.json:              "name": "Fixed8Parser"
./common/api/neon-core.api.json:              "canonicalReference": "@cityofzion/neon-core!u.fixed82num:function(1)",
./common/api/neon-core.api.json:              "docComment": "/**\n * Converts a Fixed8 hex string to its original number\n *\n * @deprecated\n *\n * parseInt(BigInteger.fromTwos(fixed8hex, true).toDecimal(8))\n *\n * @param fixed8hex - number in Fixed8 representation\n */\n",
./common/api/neon-core.api.json:                  "text": "export declare function fixed82num(fixed8hex: "
./common/api/neon-core.api.json:                  "parameterName": "fixed8hex",
./common/api/neon-core.api.json:              "name": "fixed82num"
./common/api/neon-core.api.json:              "canonicalReference": "@cityofzion/neon-core!u.num2fixed8:function(1)",
./common/api/neon-core.api.json:              "docComment": "/**\n * Converts a number to a Fixed8 format hex string\n *\n * @deprecated\n *\n * BigInteger.fromDecimal(num,8).toHex()\n *\n * @param num - the value to convert\n *\n * @param size - output size in bytes\n *\n * @returns number in Fixed8 representation.\n */\n",
./common/api/neon-core.api.json:                  "text": "export declare function num2fixed8(num: "
./common/api/neon-core.api.json:              "name": "num2fixed8"