add filter-function BuildSnippet( snippet_name )
fix lost setting during applying BuildSnippet
use snip-function
remove useless GetVar
use xpt#eval#*
add log to s:ParseSpaces()
fix duplicated ph focusing bug for Build()

bug that ph will be choosed twice:
XPT b
XSET x|post=Build('`ph^-`ph^')
`x^
fix mark escaping
remove ParseSpaces()
edge evaluation respect indent
engine use xpt#indent
engine parse snippet on parsing phase
fix filter text for UpdateFollowingPlaceHoldersWith
fix instant value indent
default value evaluation respect filter indent
embed and build is the same
refine code of indent parsing
minor refinement of s:EvalFilter
engine fix instance value building
fix fliter text indent for ActionFinish