xmake-io/xmake v2.1.9 on GitHub

Add del_files() api to delete files in the files list
Add rule(), add_rules() api to implement the custom build rule and improve add_files("src/*.md", {rule = "markdown"})
Add os.filesize() api
Add core.ui.xxx cui components
Add xmake f --menu to configure project with a menu configuration interface
Add set_values api to option()
Support to generate a menu configuration interface from user custom project options
Add source file position to interpreter and search results in menu

Improve to configure cross-toolchains, add tool alias to support unknown tool name, .e.g xmake f --cc=gcc@ccmips.exe
#151: Improve to build the share library for the mingw platform
Improve to generate makefile plugin
Improve the checking errors tips
Improve add_cxflags .., force to set flags without auto checking: add_cxflags("-DTEST", {force = true})
Improve add_files, add force block to force to set flags without auto checking: add_files("src/*.c", {force = {cxflags = "-DTEST"}})
Improve to search the root project directory
Improve to detect vs environment
Upgrade luajit to 2.1.0-beta3
Support to run xmake on linux (arm, arm64)
Improve to generate vs201x project plugin

添加del_files()接口去从已添加的文件列表中移除一些文件
添加rule(), add_rules()接口实现自定义构建规则，并且改进add_files("src/*.md", {rule = "markdown"})
添加os.filesize()接口
添加core.ui.xxx等cui组件模块，实现终端可视化界面，用于实现跟用户进行短暂的交互
通过xmake f --menu实现可视化菜单交互配置，简化工程的编译配置
添加set_values接口到option
改进option，支持根据工程中用户自定义的option，自动生成可视化配置菜单
在调用api设置工程配置时以及在配置菜单中添加源文件位置信息

改进交叉工具链配置，通过指定工具别名定向到已知的工具链来支持未知编译工具名配置, 例如: xmake f --cc=gcc@ccmips.exe
#151: 改进mingw平台下动态库生成
改进生成makefile插件
改进检测错误提示
改进add_cxflags等flags api的设置，添加force参数，来禁用自动检测和映射，强制设置选项：add_cxflags("-DTEST", {force = true})
改进add_files的flags设置，添加force域，用于设置不带自动检测和映射的原始flags：add_files("src/*.c", {force = {cxflags = "-DTEST"}})
改进搜索工程根目录策略
改进vs环境探测，支持加密文件系统下vs环境的探测
升级luajit到最新2.1.0-beta3
增加对linux/arm, arm64的支持，可以在arm linux上运行xmake
改进vs201x工程生成插件，更好的includedirs设置支持

Bugs修复