Added schema caching to Schema.cs
Added schema caching to Schema.cs

How it works:
Schema web connection is opened and headers read.
If cache file is not present or its creation time is older than "Last-Modified" of web schema Schema is pulled from api.steampowered.com, put into cache file and  cache file creation time is set equal to Schema Last-modified.
If cache file is present and is up-to-date the Schema is downloaded from the file.
Update SteamTrade/Schema.cs

Fixed indentation, changed cache file name.
Change Output Path of SteamBot.

- Output path now matches documentation. Goes to <projectroot>/Bin
- Update README with more information and remove old information.
- Remove old SLN file and add a configuration template file for release
builds.
Added extra error checking before adding item to trade
Merge pull request #136 from Payme/master

Extra error checking before adding items to a trade
Fix for wrong bot behaviour being used.
Merge pull request #134 from cwhelchel/fix/cfg-file-loc

Fix for bad placement of config file.
Merge pull request #131 from lazy1/master

Schema caching was added to SteamTrade/Schema.cs
Merge pull request #138 from Payme/master

Wrong bot behaviour being used when multiple bots.
Fixed Bug on RemoveAllItemsByDefindex().
- It wasn't removing any items.
- note: bug introduced in ce285d96e9a9f9b00b685ad925e0fe7347829757 along with RemoveAllItemsByDefindex().
Merge pull request #154 from omega32/master

Fixs Bug on RemoveAllItemsByDefindex()
Updates SteamKit2 Dependency
Implemented OnFriendRemove() callback.
Removed OnFriendRemove() remark in the in-line documentation.
Merge pull request #172 from spideyfusion/spideybot

Implemented OnFriendRemove() callback.
Adds IsFreeToPlay() To Inventory.cs #67

Creates a method to check if a user's inventory is free to play. This
fixes Issue #67: https://github.com/Jessecar96/SteamBot/issues/67

Tested on my inventory, and a free to play's inventory.

This does take into effect the comment of a Free to Play can use
Backpack Expanders.
Revert "Adds IsFreeToPlay() To Inventory.cs #67"

This reverts commit 0b0c85fdb8c8f951e3de1a2e3f1ecf52e9cdbb49.
Adds IsFreeToPlay()

Adds a function to determine if a user is FreeToPlay or not.
Merge pull request #179 from gamemaster1494/ExperimentalThings

Adds IsFreeToPlay() Function In Inventory.cs